I would say 8x10 should be the max, not that I mind bigger prints, but the cost of shipping etc, would add up with something so big.
If we are going to do this, then I think we should all chip in for the portfolio, is not fair to Brian to make him take this cost.
As to the critique I think that defeats the idea of the exchange, this would be scanned prints which I find lacking. If there is something we absolutely have to say about a print I guess we can always add a little note. I dont know I guess this is something we can leave up to the group once we get going. I would rather not participate in a critique either giving or receiving but I suppose some people like this and it might be a good option for them.