For now, the best source of detailed documentation of the sort you're looking for is external to the system.
There's a "course card" available
www.coursedirect.com
Alice 2.0 CourseCard
ISBN: 1-4188-4675-9
Retail single copy $3.60
There are also two textbooks (obviously more expensive):
1)
"Learning to Program with Alice"
Wanda Dann, Stephen Cooper, and Randy Pausch
Publisher: Prentice Hall
ISBN: 0-13-187289-3
NOTE: although I am an author on this book, I donate all my royalties back to Carnegie Mellon to help underwrite the software development costs.
2) (not yet available, estimated late March)
An Introduction to Programming Using Alice Charles W. Herbert
ISBN: 1-4188-3625-7
I believe both books are (will be) available through
www.amazon.com
I'm sorry we don't have a detailed, free "language reference" sort of thing; we have limited staffpower and haven't done that yet.