What offset would I need to make this work ?

-D

Depends on the spoke design. All wheels are different. Either you buy wheels that you know will already fit or you have to try it out yourself.

Yes, but you can actually calculate if it will fit or not using wheel & brake dimensions & offset. You dont have to physically put the wheel on just to find out.

Yes, but since every wheel has a different spoke design (ie. different spoke width), the necessary offset will vary. Do you even have a specific wheel and size in mind? Of course the narrower the wheel is, the higher the number of offsets that'll work.