I'm glad that you have got your links working but, just for the record, in my own tests, the slash is required for Safari 5.1.7 on PC (although Safari on PC is more than a little outdated now, the last update being over two years).

The following formats should work in all browsers:

linkURL="http://www.example.com/gallery/#2"
linkURL="http://www.example.com/gallery/index.html#2"

As long as the 'wp-juicebox' folder is in your WordPress 'plugins' directory (and the 'wp-juicebox.php' file is inside the 'wp-juicebox' folder), then the plugin should be listed on your Dashboard -> Plugins page.
Please double-check that the 'wp-juicebox' folder is in the correct location on your web server.

The theme you use should have no bearing on whether or not a plugin shows up in the list but, being that you are experiencing difficulties, you could try temporarily reverting to the default WordPress theme to see if this makes a difference.

I would be happy to offer more help but in order to investigate further, I would need to see the problem for myself which would require access to your WordPress installation and your web server.
If you are agreeable to this, then please email me the URL and login details to your WordPress installation and the FTP login details to your web server and I will take a look and try to figure out why the plugin is not showing up.

In the meantime, if you like, you can manually embed Juicebox galleries into your WordPress pages or posts using the baseUrl method of embedding as documented here.
Essentially, you would create a Juicebox-Pro gallery using JuiceboxBuilder-Pro, upload your entire Juicebox gallery folder (not just the contents) to your web server and then paste the baseUrl embedding code into the body of your WordPress page or post (ensuring that the method of entry is 'Text' rather than 'Visual').
It does not matter where on your web server you upload your gallery folder to as long as the two paths in the embedding code (the path to the 'juicebox.js' file and the baseUrl itself) are correct.

No. Juicebox-Lite and Juicebox-Pro galleries both display on Android devices equally well. (Likewise with SimpleViewer-Standard and SimpleViewer-Pro.) There is no distinction between embedding a Lite/Standard (free) version and embedding a Pro version .

A blank screen on a mobile device usually implies one of two things:
(1) JavaScript is disabled in your browser.
... or:
(2) You are using a 3G connection (rather than wi-fi) to view your gallery.

This suggests that the problem is not (1) above.
If you are trying to view your gallery over a 3G connection, then please see this FAQ which contains a solution to the problem.
Why can't I view my gallery on a 3G mobile connection?

You should be able to add Pro configuration options manually by specifying the settings in optionName = "optionValue" format within the advanced module settings ('Pro / Manual Configuration Options').
Please note that we did not write the Juicebox module for Drupal ourselves and support for the module would be better directed towards the Drupal forum where the author of the module should be able to help you further.

Try one of the two following suggestions:

(1) Use an opaque (rather than transparent) expandedBackgroundColor (in JuiceboxBuilder-Pro's 'Customize -> Color' section). For example, try setting expandedBackgroundColor="rgba(255,255,255,1)" (make sure that the 'Opacity' value is set to '1'). This should ensure that no elements from your web page are visible when the gallery is expanded.
... or:
(2) Set expandInNewPage="TRUE" (in JuiceboxBuilder-Pro's 'Customize -> General' section). When the gallery is expanded from the Splash Page, it will be displayed on a page of its own rather than on top of the embedding page.

Hopefully one (or both) of these suggestions will be a suitable solution to your problem.

It is not possible to have the shared image's thumbnail displayed in the pop-up share window due to limitations imposed by Facebook on what data can be passed via their share URL. Only one thumbnail can be used per web page. (The link will still point towards the correct image within your gallery, though.)

The image used in the Facebook sharing pop-up window can be set using an Open Graph og:image <meta> tag in the <head> section of your web page, such as the following:

<meta property="og:image" content="http://www.example.com/images/thumbnail.jpg" />

If you create a gallery with JuiceboxBuilder-Pro, an og:image tag will be automatically generated and included in the gallery's 'index.html' file. If you are embedding your gallery in an existing web page alongside other content, then you will need to add an og:image tag manually.

Thank you for the additional information.
I have now been able to replicate the problem. It seems to happen in IE8 and IE9 when imageTransitionType="SLIDE" (the default value for this configuration option).
I have logged a bug report with the developers and it should hopefully be fixed in the next version of Juicebox.
In the meantime, it looks like a suitable workaround would be to set imageTransitionType to something other than SLIDE (FADE, CROSS_FADE or NONE).

If you require an invoice for your purchase (as a PDF document), then please fill in this Juicebox-Pro Invoice Request Form.
Thank you.

In Touch Input Mode (on mobile devices), a tap on the screen (anywhere other than on a button) will toggle the overlay on and off. (Images can still be navigated by swiping left and right.) It sounds like this might be what is happening.
Try setting showInfoButton="TRUE" (in JuiceboxBuilder-Pro's 'Customize -> Button Bar' section). This overrides the default behavior for the overlay and it will be toggled on and off only when the user clicks on the Info Button on the Button Bar.

What you are referring to is likely to be the SEO Content produced by JuiceboxBuilder-Pro. It is selected by default but you can switch it off by deselecting the 'Add SEO Content' checkbox in the 'Customize -> Sharing' section.
This code is used purely for Search Engine Optimization reasons and is not actually required for the gallery itself at all. Please see the SEO support section for further details.

@jtmpusr

Thank you for your suggestions.
Here are some notes on a few of your topics.

With Juicebox-Pro, you can have multiple rows of thumbnails by increasing maxThumbRows from its default value of 1.
For reference, a list of all available thumbnail configuration options can be found here.

You could source your gallery using a Flickr account and tag your images in Flickr.
Each link in your web page could use JavaScript to set the Juicebox configuration option flickrTags in the gallery's embedding code accordingly and then reload the gallery using the selected tag or tags.

JuiceboxBuilder-Pro (which comes with Juicebox-Pro) has a number of preconfigured gallery layouts known as presets which you can choose from. Many of the presets available will allow you to instantly configure your gallery to look like the demo galleries on this web page. For more information about presets, please see the JuiceboxBuilder User Guide.

I have not been able to replicate this behavior in any test galleries of my own in IE11 (or in IE9 Document Mode within IE11).

Also, do you see the problem in any of our own demo galleries on this web page or just in your own gallery?

There might be an element on your web page which is partially obscuring the thumbnails (which, for whatever reason, is only a problem in Internet Explorer). You should be able to see if this is the case using a browser's developer tools (usually F12).

It might also be wise to check your web page for HTML errors using the W3C Markup Validation Service.
If there are errors on your web page, it might be worth trying a different WordPress theme to see if this makes a difference.

It might also help to ensure that your version of Juicebox-Pro is up-to-date.
Juicebox-Pro v1.4.1 has just been released so please try upgrading your WP-Juicebox plugin to Juicebox-Pro v1.4.1.
Instructions on how to get download the latest version can be found on the Upgrading Juicebox support page and instructions on how to upgrade WP-Juicebox can be found here.