Gingerbread is the name of the latest version of Android.
As for custom roms, there aren't a lot for the pro like a lot of phones have, but there are a few. Check this forum for everything about rooting, custom roms, and hacking in general: Droid Pro Hacks
It sounds like you're pretty new to all of this, so if I were you, I'd do some reading about everything before jumping into it. Before you start messing around with the way your phone operates, you need to know exactly what you're getting yourself into. This is particularly the case with looking for custom roms for the Droid Pro since there aren't many and what is out there now can be a bit on the buggy side. Google is a great tool for search about various aspects of this. You'll find some good basic info here: Droid Hacks
We have only one wworking rom at this point and that is CM7 (cyanogenmod).
Check the above link.
But be sure to do a lot of reading before going further as in many cases of customising it is not for the faint of heart.
Or so I was told lol.
I just wanted my phone to run smooother so I went for it.