what size are the packages usually?
which size box should i get the 3"x5.5" or 5"x5.5"? (they're all a foot or so deep)
do they come in hard boxes or flexible packages/envelopes?
They ship to a PO Box. They come in standard mail size. I have gotten plenty and that's all I am saying. Don't want to say too much but you will be happy.