Sahil.
You can go to
http://airbusdriver.net and download technical notes from there. You can also try
www.smartcockpit.com and download FCOM from there, specially FCOM I and read the chapter on Autoflight.
To answer your questions:
1) NO, you have to calculate it either from the hard copy of RTOW charts for the particular runway or from a software inserting the ambient conditions or worst case scenerio from the FCOM 2.
2) Yes.
3) Thrust lever is fixed in CL (climb) gate and Auto thrust can change power anywhere between idle to climb (assuming no single engine operation, during single engine it is kept in MCT and thrust can vary between idle and MCT).
4) No, autothrust manages the thrust to maintain speed.
5) Flying the aircraft manually does not cause discomfort to passengers, it all depends on your flight techniques and smoothness, the earliest the airbus pilot can engage autopilot is at minimum 100' RA and min 5 sec after liftoff (both conditions must be met).