Welcome, Gary,
On the drum/cymbal roll question, we just had this discussion in the Music Creator forum:
http://forum.cakewalk.com/tm.aspx?m=2462866 Due to characteristics of the sound samples used in Studio Instruments Drums (the drums you have in GTP4), it is difficult if not impossible to get a good roll, particularly with the cymbals.
I highly recommend downloading Session Drummer2. It is cheap($10 download), and offers much more flexibility.
To give you an idea, the looser sounding snare in this song is from SD2:
http://soundclick.com/share.cfm?id=11243952 As for a comprehensive manual, the help files are your best bet.
They don't explain techniques, but tell you what's what.
Also check the Sonar Home Studio and Music Creator forums. Home Studio 7 and Music Creator 5 are functionally very similar to GTP4. Most questions/answers would apply. Plus, these forums are a bit more active.
if you have questions on particular functions, post them. We can provide fairly concise answers if the question is more focused.