Darren's right. We have a wiki that answers pretty much everything you need to know, and you could read it and do what it says in less than an hour.
http://wiki.ppcgeeks.com/index.php?title=Sprint_Epic_4g
And as far as which ROM to flash, that's like asking someone which car to drive or which soft drink to buy. Everyone has their personal likes and dislikes. Now, having said that, I really like the midNIGHT ROM that ptfdmedic has created. Its fast, stable and has the best battery life of any Froyo ROM I've tried (and I've tried just about all of them). Click on the banner in my sig and it will take you there.