My opinions:
I think that's fine as the only rule for a crafty swap
For the other swap, I think the past limits (around $20 if I'm not mistaken?) would work
I think whether it is Christmas-themed should be up to the sender (and determined through the Q&A thread)
And as for a date, I think aim to have it there by Christmas. It might miss the mark a little, Christmas post is notoriously tricky, but hopefully the majority will arrive on time so we have something else to open on the day