Azzuri,
A good place to start would be the FAA ATP practical test standards. You can get a copy of these from Sportys, Jeppesen, or ASA. All available over the web.
Flight planning for your aircraft.
Alternate requirements. (part 135/121)
Systems, limitations etc
MEL BD700
performance BD700
weight and balance BD700
privilages and limitations of ATPL licence holder (part 61 of regs)
The Practical Test Standards will give you a fairly good clue on what knowlegde/skills you will have to demonstrate in the sim and in an oral.
Best of luck.
MJB