I rooted my HTC EVO 4G and I get a lot of information from
http://forum.xda-developers.com/forumdisplay.php?f=1015I flashed a MikMik rom and he has a ton of "goodies" for the EVO 4G
At to updates, most developers create new roms, or update their current rom to include the OTA updates. Mik did this on the rom I am using, so although you cannot update with OTA it doesn't take these guys but a day to update
I really enjoy the different themes and looks that can be done after rooting, and now my battery life is incredible and got ride of all the bloatware that the manufactures put on the phone
Find your particular phone on XDA and have fun