#1 Yes, you can use custom HTML in the side menus.
#2 We have a couple forums here that can help with some style downloads, and tips on modifying. There's also UBBdev.com if you want to go into deeper modifications. It's mainly just stylesheet and some graphics it looks like for the site you referenced.
#3 Yes, we actually install our latest version and then import all of your data into it, so it won't matter if you have IIP installed.
#4 We don't need much lead time, installs and upgrades are normally complete within 3 days of the order being placed.
