I decided to proceed with the price. Pricey but the contractor works has been proven (by my friend) as neat, clean and good quality.

But for the info, i have answered your questions as below:

Color combination - only 1 color for wall&ceiling, different color for doors/doorsframes
Ceiling height - living/dining 11.25ft, rooms 10.25 ft
Coats - 2 coats but depends on condition if requires more than the contractor will do more coating
Painting doors and doorframes - water based paint, use roller and brush, sanding if required
In general, he will touch up first before painting the wall/ceiling