I just went through and did exactly what you're asking about. Removing the pre-loaded apps, like Sprint Nascar, does require Toast's rooting method. Furthermore, even after doing that, all the removal has to be done via the command prompt with ADB while in recovery. It's a bit of a pain, but I finally decided to go ahead and bite the bullet since I was tired of seeing all that Sprint crap in my app drawer.
The only two things that I can say for sure that you shouldn't remove, aside from the obvious stuff like the dialer, is the stocks app and the news app. I know that sounds weird, but if you remove them then you won't be able to access the Accounts & Sync settings. I also think I remember reading that removing FriendStream can cause a few issues as well.
I suggest using ADB's pull command to copy any apk file that you're going to delete from your phone so you can push it back onto the device if something weird happens after removing it. I made the mistake of forgetting to do that, and I had to reflash to get back to normal. Also, if you're going to go all out and do the Toast root and recovery, MAKE A NANDROID BACKUP!
Lastly, take everything that I just said with a grain or two of salt. Beer and oxycodone can cause typing problems.
