1) leave TP7 and jump to Free Pascal - it is crossplatform and 98% compatible with TP
2) what kind of bitmap? 8/16/32? This is a good "unit" for such stuff.

If you still want TP7, jump to Programmer's heaven, there are tons of bitmap processing units for TP7.

However, if you want to program games, choose any good api or library (like Phoenix for 2D games, SDL, OpenGl etc.) and checkout articles and forums on this site