Here are few questions for which I was searching answers on vb.com/org and some other forums. I hope I will get a correct direction here, as you have implemented most of these things here

1. Reduce/adjust forum row hight (forums that we see on forum home)
2. Reduce threads, posts etc columns widths
3. Remove post and status icons

For the icon key, you can just remove that code from the templates. I don't have a default vBulletin skin anywhere to look at, so I'm not sure of the exact code. You can do a search for 'icon key' and find some of it.

The simplest way to replace the actual icons would be just to replace the images with transparent gifs of equal size.

http://www.vbulletinzone.com/t9/ shows you how to remove the icon keys