Am beginning to slowly think about adding alt processes with a contact print frame. S-l-o-w-l-y starting in this direction 'cause I've been a confirmed and happy inkjet printer. So this is a complete new-to-me deal.
I have 2 questions:

1) Contact Print frame: If you buy one big enough to do what you might want later, can you use an oversize frame for smaller prints without a problem?
2) Vacuum Print frames: Is this necessary? or does it become necessary at a certain size? I'm seeing plenty of folks do just fine with even VERY large contact frames without vacuum (or at least apparently without vacuum assistance). What pushes for the change of a vacuum assisted image registration? Delicacy of the paper?

Thanks!