WordPress.org

I can see elements of my site through the overlay

It's a problem of z-index. Check the z-index property for the problematic elements, and force them to be less than 100. (Thanks dway!)

How do I add images to a post?

Inserting Images into Posts and Pages

How do I create a thumbnail gallery?

Upload images to a post (see previous question) and use WordPress' built-in gallery shortcode: [gallery link="file"]

Note the link="file" - this is crucial! By default the gallery will link your humbnails to a page displaying your image. With link="file" the thumbnails links directly to the image files - allowing Lightbox to function.

Must fade-in and animation of all *box-scripts be so slow?

WP-jQuery Lightbox lets you configure the animation duration and disable image resizing from the admin panel. Set duration to 0 to disable animations entirely.

Can I help you in any way?

Indeed you can!

Translations and help with implementing them would be nice. A read through and comments on my WordPress API usage would also be most welcome, as I'm not really able to keep on top of the frequent WordPress releases anymore.

And of course; a book or two always brightens my day! (used ones are fine!)