mod_rewrite is a search engine optimization. It's actually a function in apache, there just tons of mods that do that, but I think the best one out there is the one made by able2know.com

The bantron should be installed. It's a better way for the admins to ban people. Also, you pointed out that the yellow card one is not require, and I guess it's true, I think it's only useful when you have tons of people on a forum. The attachment mod is a must....just install it, you'll see. At cosa it was use to upload schalorships, flyers, and a few other things.

Edit:
here's the link:
http://www.able2know.com/go/?a2kjump...5478&view=File

and here's the thread:
http://www.able2know.com/forums/about15132.html