Hello,
I would recommend the reviews I carried out in issue 2 for
Image and Gallery module reviews each of these comes with it's own tutorial videos so it will help you to quickly get started using the module.
I personally like Scott McCullochs Gallery module, but I would have a look at each of the modules reviewed and see what matches your own needs.
Documentation module, have you had a look at the new free core project Repository module, check it out here:
http://www.dotnetnuke.com/Default.aspx?tabid=831
In fact, you may be able to use the repository module for both of your tasks.
Hope this helps,