Welcome El Mallorquin!
You're asking some good questions, things that a number of us have struggled with before. Rather then rehash a lot of stuff that has been done before, a quick search of
this forum and the
Engine Rebuilders Forum will bring up a lot of information that will provide hours of interesting reading for you.
I don't think you'll ever find a "doing this is best" answer, but you will find a lot of insight that will help you make the best decision for your application. As far as cams go, I suspect that the three choices (S or RSR or Sprint) range from agressive street (S) to all out race (RSR or Sprint). You might want to read through
this thread for some ideas how selecting the best cam for your application. A number of great people helped me out in pulling it together.