By default, a Splash Page is displayed when a gallery is embedded at less than 100% x 100% and displayed in Small Screen Mode.
The Splash Page is not displayed in the iframe gallery as the gallery is actually embedded (at 100% x 100%) into the HTML page being loaded into the iframe.
If you use the standard embedding code and do not want to use a Splash Page, then you can set showSplashPage="NEVER" (in JuiceboxBuilder-Pro's 'Customize -> Splash Page' section).

If using local images, you can set the dimensions of your gallery's thumbnails by clicking the 'Change Sizes...' button on the 'Images' tab. New thumbnails will be generated at the specified dimensions and the thumbWidth and thumbHeight configuration options will be set accordingly. For a Flickr gallery, just open your gallery's 'config.xml' file in a plain text editor and add entries such as thumbWidth="100" and thumbHeight="80" to the opening <juiceboxgallery> tag.

A Juicebox gallery's dimensions do not change when clicking on a thumbnail image and it is not possible to treat the thumbnail page in Small Screen Mode like a Splash page (expanding the gallery on a thumbnail click).
It might be possible to achieve this (using the Juicebox-Pro API, CSS and JavaScript) but you may run into complications with the normal hide/show thumbnails and expand/close gallery functionality. You might need to use some variables to keep track of the expanded state of the gallery and the visibility of the thumbnails to avoid unnecessarily closing the gallery (via the toggleExpand() method) when a user clicks on a thumbnail whilst in expanded mode. It might become very complicated very quickly.
Perhaps the best option would be to disable the Splash Page (if you do not want to use it) and display the Expand Button (by setting showExpandButton="TRUE" in JuiceboxBuilder-Pro's 'Customize -> Lite' section) so that users can expand the gallery fullscreen by clicking the button. (Please note that the Expand Button is disabled when using an iframe. This is noted in Option #2 here.)

On the 'Images' tab of JuiceboxBuilder-Pro, you can drag and drop thumbnails into a new order.
You can also use Ctrl+Click to highlight a selection of images or Shift+Click to highlight a block of images and then drag and drop the highlighted images into a new order.

You can also sort the images using the 'Images -> Sort' option from the drop-down menu at the top.
Possible values to choose from are 'By File Name', 'By File Date' and 'Reverse'.

Yes. Just edit the first post in the thread and type "[SOLVED]" at the end of the 'Topic subject'.

If you want to allow a user to start and stop an automated slideshow, set showAutoPlayButton="TRUE" (in JuiceboxBuilder-Pro's 'Customize -> Button Bar' section) and the AutoPlay button will be displayed in the gallery's Button Bar.

If you want the slide show to start as soon as the gallery is loaded, set autoPlayOnLoad="TRUE" ('Customize -> AutoPlay').

If you want to have the images loop (instead of the slide show stopping at the last image), set enableLooping="TRUE" ('Customize -> General').

You can change the image transition type and image transition time using the imageTransitionType and imageTransitionTime configuration options ('Customize -> Main Image').

Other AutoPlay options (such as displayTime) can be found in the 'Customize -> AutoPlay' section.
Please see here for a list of AutoPlay options.

In order to investigate further, I will need some more information. Please post the URL to your WordPress website so that I can take a look.
It would also help if I had access to your WordPress installation and web server. If you are willing to allow me access, please let me know and I will send you an email so that you can provide me with your login details. Thank you.

As all your image titles are just a single line of text, it might be easier to just increase the maxCaptionHeight so that the text is vertically centered within the caption area.

Otherwise, to vertically center an image title using CSS, you could try something like the following:

.jb-cap-content.jb-caption-title  { 
    position: relative;
    top: 50%;
    transform: translateY(-50%);
    -ms-transform: translateY(-50%);
    -webkit-transform: translateY(-50%);
}

@come_paglia

It looks like the following should work on your web page:

#nav li.menu-item  { 
    z-index: 9999;
}

On further investigation, the problem was not in finding a suitable CSS selector to attach the click handler to (the correct class is .jb-idx-thumb) but the fact that the class does not exist in the Document Object Model immediately after the Juicebox-Pro API event onInitCompete is fired (when the gallery should be complete and ready). The trick is to delay the setting up of the click handler (until such time as the .jb-idx-thumb class exists in the DOM) by using setTimeout.
Try the following which will open the current image's corresponding linkURL when either a thumbnail or main image is clicked.

<script>
    var jb = new juicebox({
        changeImageOnHover: 'TRUE',
        containerId: 'juicebox-container',
        imageClickMode: 'OPEN_URL'
    });
    jb.onInitComplete = function() {
        setTimeout(function() {
            $('.jb-idx-thumb').click(function() {
                var index = jb.getImageIndex();
                var info = jb.getImageInfo(index);
                var url = info.linkURL;
                window.location.href = url;
            });
        }, 500);
    };
</script>
<div id="juicebox-container"></div>

I have logged a bug report with the developers (regarding the fact that the gallery is not complete and ready immediately after onInitComplete is fired) and it should hopefully be fixed in a future version but the code above should work fine in the meantime.

The following demo gallery layouts are included as presets in the current version of JuiceboxBuilder-Pro: Colors, Embedded, Full, Hong Kong, Sharing, Simple, Slider, Top Left. (They can be selected from the 'Load Preset' drop down menu on the 'Customize' tab).

The XML files for galleries can usually be found manually by adding 'config.xml' to the demo gallery's URL.
For example, the 'Flat' demo gallery can be found here: http://www.juicebox.net/demos/pro/flat/
The 'Flat' demo gallery's XML file can be found here: http://www.juicebox.net/demos/pro/flat/config.xml

If you save the 'Flat' demo gallery's XML file to your hard drive, then you can open it as a preset via the 'Presets -> Load Preset...' option from the drop-down menu at the top of JuiceboxBuilder-Pro.

@BrianP6

When the bug is fixed, it will be fixed for all browsers on all devices.
If you are asking if, currently (with the bug present), setting expandInNewPage="TRUE" will fix the bug on mobile devices, then yes, it will.
Setting expandInNewPage="TRUE" forces the gallery to be expanded on a new page of its own where the code from the embedding page can no longer conflict with the gallery's own code.
However, if you are using Juicebox-Lite, then your gallery will be using expandInNewPage="AUTO" (the default value for this configuration option) and on iOS devices, this setting will automatically expand the gallery on a new page anyway to avoid issues with incorrectly scaled content when switching between regular and expanded mode. Please see the Expand Gallery Behavior support section for more information.

@ErikC & rounders

Thank you both for the additional information.
It looks like the problem is unique to Mobile Safari in iOS 8 (or at least iOS 8.0.2).
I have notified the developers of this and they will investigate further.

As I am unable to replicate this problem myself, I would appreciate some more information in order to narrow down the possible causes of this problem. (Perhaps the problem is specific to a certain browser under a certain version of iOS.)
If you could answer the following questions, that would be great. Thanks.

(1) What generations of iPad and iPhone do you use and what versions of iOS do they run?
(2) Do you see the problem happening in both Mobile Safari and Chrome or just in one browser? (If you have not yet tried Chrome, please do so to see if this makes a difference.)
(3) Does this happen only in pages with a Juicebox gallery or have you seen this happen in any other scrollable web pages which do not contain a Juicebox gallery?

As you have discovered, you won't be able to put PHP code into the body of a WordPress code and have the code run.

Your style variable is currently a string (enclosed in quotes). It needs to be an object. Remove the surrounding quotes. (Also, there is no need to escape the double quotes.) Try the following:

var style = {
    baseUrl : "http://hella-stroh.de/jbgalleries/startseite/startseite/",
    containerId: "juicebox-container"
};

With regard to the common configuration options, the juicebox_style variable in your 'startseite.js' file is also currently a string rather than an object. It is not possible to add names to the Juicebox object as a string (like the PHP example). The PHP example slots in a chunk of text (server-side) before the code is parsed by the browser (client-side). The embedding code is fully formed (by the server-side PHP) before the browser even sees it. This is not the case with your JavaScript code.

Create an object with all your common configuration options (like the style object above) and then merge the two objects before feeding it to your new juicebox line. (You can keep the common configuration options object in your external JavaScript file but it should be an object rather than a string.)

For example:

var style = {
    baseUrl : "http://hella-stroh.de/jbgalleries/startseite/startseite/",
    containerId: "juicebox-container"
};

var common = {
    autoPlayOnLoad: "TRUE",
    showThumbsOnLoad: "FALSE"
};

for (var name in common) {
    style[name] = common[name];
}

new juicebox(style);