I am just starting myself, but ...
Please watch the two Jan videos
forward:
http://telerikwatch.com/2008/10/telerik-watch-minute-interview-with-jan.html
reverse:
http://telerikwatch.com/2008/11/telerik-watch-minute-openaccess-orm.html
DB RM is reverse with no collections, just start accessing...
OOM you will use the front end partial classes to establish the derived behaviors, if reverse or apply attributes if forward.
Stored Proc's is a good question. I just did a quick look in the wizard and did not find anything. So, per the manual, stored proc' are access using OQL.