[Q] Questions about porting roms to a device

I am learning to port roms and have some questions
1. Can i take cm7 as base rom and cm9 as port rom
2. What are the requirements for that should be same on both devices i mean should the processor speed, resolution, screen size, ram be exactly same on both devices
3. Do both devices need to be arm v6
4. What is the best device to port roms to Htc wildfire buzz

Sorry for my bad english