There is no limit to the number of Juicebox galleries you can embed on a single HTML page.

Check that you actually have a <div> with id="juicebox-container3" on your page.
If you do, then please post the URL to your web page so that I can take a look and help further.

The functionality of the Splash Page cannot be changed but you can display your galleries where they are embedded in mobile devices by setting screenMode="LARGE" in your gallery's XML file:
If using JuiceboxBuilder-Pro to create or edit your galleries, the screenMode option can be found in the 'Customize -> General' section.

Yes. The jAlbum, Photoshop, Picasa and WordPress plugins have all been updated to Juicebox v1.1.1 but the Lightroom plugin has not yet been updated. It will folow shortly.
However, if you have replaced the 'jbcore' folder from the current Lightroom plugin with the 'jbcore' folder from the Juicebox-Pro v1.1.1 download package, then your galleries will be Juicebox-Pro v1.1.1 galleries and you can safely ignore the 'v1.1.0' label in the interface.

Thumbnails should always be created and displayed with WP-Juicebox. (There is no setting in the interface to prevent this from happening.)
However, the thumbURL entries in your gallery's XML file (http://wwwsevenarrows.zippykid.it/wp-co … box/10.xml) are empty.
Try editing the post containing the gallery and 'Update' the post which should regenerate the XML file.

This bug has now been fixed in v1.1.1. Please see this Juicebox Blog entry for further details.

Both of these bugs have now been fixed in v1.1.1. Please see this Juicebox Blog entry for further details.

@KR64

The tooltips and on-screen messages are embedded within the 'juicebox.js' JavaScript file which is packed and obfuscated (and Juicbeox-Pro does not come with source code) so it would not be possible to modify the file and display the text in a different language.
However, thank you for the suggestion.

@jb_newb

Try swapping the baseUrl of the 3rd gallery with that of a gallery you already know displays OK to determine whether the problem is with the gallery or with your gallery-changing mechanism. Also, try using the baseUrl of the 3rd gallery in the 2nd gallery's embedding code to see if it displays there. This should at least tell you where the problem lies.

Also, a few tips:
(1) Your web page loads the 'juicebox.js' file from all three galleries. It is necessary to load only one (as they are all identical).
(2) Your galleries are Juicebox-Lite v1.0.2 galleries. You could upgrade them to the current version of Juicebox-Lite (v1.1.0) as many bugs have been fixed since v1.0.2. Please see the Juicebox - Version History for details. The current version of Juicebox-Lite can be downloaded from the link on this page.
(3) You should fix the HTML errors on your web page. You can validate the page with the W3C Markup Validation Service and then fix the errors reported. Once the code validates, your web page should be displayed with greater predictability and consistency across different browsers.

The first two images may have exactly the same width but the length of their corresponding captions differs slightly.
When using captionPosition="BELOW_IMAGE", the width of the caption area equals the width of the image so when a narrow image is being displayed, the caption may be split into more than one line.
Other than changing the captionPosition to OVERLAY, it is not possible to increase the width of the caption area.
However, you could decrease the font size of the caption (so that it all fits on a single line) by using something like:

<caption><![CDATA[<span style="font-size: 11px;">Charcoal on Paper "22.5" x "36"</span>]]></caption>

Alternatively, you could change the font-size globally for all captions by opening the 'jbcore/classic/theme.css' file in a plain text editor and changing the 'font-size' on line 201.

As far as I am aware, there are no immediate plans to incorporate Juicebox-Pro options into the interface of the Lightroom plugin, though it is technically possible and may be considered some time in the future.

If there is a certain combination of Pro Options that you use for all of your galleries, you could edit the plugin's 'juicebox.lrwebengine/config.xml' file and add the Pro Options as attributes to the opening <juiceboxgallery> tag so that each time you create a gallery with the plugin, these Pro Options are used and included in the generated gallery's XML file. This may save you from having to edit XML files after you create each gallery.

Set your gallery's width to 100% and try using the following structure on your web page:

<div id="wrap" style="width: 100%;">
    <div id="left" style="width: 25%; float: left;">
        <span>Content for left side of screen goes here</span>
    </div>
    <div id="right" style="width: 75%; float: right;">
        <div id="juicebox-container"></div>
    </div>
</div>

Are you trying to embed a Juicebox gallery in a theme's header?
If so (and you know the gallery id you wish to display), you should be able to use the following code in your theme's 'header.php' file.

<?php
    $JB = new Juicebox();
    echo $JB -> shortcode_handler( array( 'gallery_id '=> '2' ) );
?>

... changing the '2' above to the gallery id of your choice.
Alternatively, the following should also work:

<?php
    echo do_shortcode('[juicebox gallery_id="2"]');
?>

As you have discovered, the gallery's dimensions are tied to the gallery (being stored in the gallery's XML file) and a single gallery cannot be displayed twice with different dimensions each time. In fact, the same gallery should not be displayed twice on the same page because both galleries will create divs with identical names to be embedded into.
I would recommend creating a separate gallery for your theme and, if necessary, duplicating the gallery (with different dimensions) for use elsewhere.

The problem with your original code seems to be the extraction of the gallery id from your custom field as entering the code above (with the hardcoded gallery ids) seems to work fine. However, I would need to know more about the custom field you are using to help with the extraction process.

What is output if you echo $juicebox after defining it on this line:

$juicebox = get_post_meta( $post->ID, 'slideshow_embed', true);

For your subsequent code to work, the output would have to be something like: [juicebox gallery_id="2"]