Q 43:
by RAW, you can't do that, so that means we get to stretch interpretations anyhow.
first, assume that the item was made by a druid with said feat. second, take the creature you wish to summon, and compare it's challenge rating to the summon nature's ally table.
pick the higher level one.
then, base cost off of a one-use item of that spell. add greenbound summoning to item pre-req.