[Asterisk-Users] documentation?

[Rich Adamson]

Been learning * now for a couple of weeks and have all basic features 
running including VM, MoH, FX lines, iaxtel, and FWD. However, I seem to be 
lacking documentation on a lot of technical things and am wondering if I 
overlooked something that is obvious to others. (I do have the Handbook,
have been doing a fair amount of google searches, and read the README.*
files.)

Examples,
Where should I have learned that *8# is the call pickup dialing sequence?

Other then *8#, are there other preprogrammed sequences (I assume there is)
in a stock * implementation?

Where should I have learned about the "t" and "r" in:
 exten => s,1,Dial(SIP/3000,20,tr) 
and all the other possible options in various * config statements?

Rich