Im interested in going film medium format with a 645 AFD and dont know anything about Mamiya systems or film really.

A few Q's if someone can help:

1.) Will the Mamiya-Sekor 80mm 1.9 fit/work on the newer 645 AFD (either I or II) cameras?

2.) Which flashes work with the 645 AFD's? Any flashes that offer something like a TTL for the Mamiya 645 AFD? Will Canon flashes work with them?

3.) Push/Pull processing: I am used to digital and it's ability to quickly change iso. So with film, what is you favorite ASA to be able to still push or pull 2-3 stops for added versatility in changing light situations (especially from day to low-light)

4.) What happens when you "pull-process" 3200asa film all the way down to say 200-800asa? Is the degragation worse than "push-pulling" (ie:400 pushed to 1600 or 3200asa, etc.)

5.) Multiple backs with different ASA film for versatility: What is your favorite combo/or what do you recommend if you have for example 2 backs (one on camera and an extra in your bag or pocket)? (ie: 400asa on camera and a back with 3200asa as a backup)?

6.) Whats a good quality scanner that is affordable (aka: not over $1k)?

any help appreciated!