I believe the "follow 10 before" rule, is just so that everyone gets new followers, but you can certainly follow as many accounts as you like - I plan on following all of the people above me!
I would imagine that pinning directly from etsy would help the shops relevance more than pinning from pinterest, but I think either way it brings more exposure to the shop! For me, personally, if the person has a pinterest board for their shop, I'll be pinning from there since I imagine those are items they would like to promote. If they don't have a "shop" pinterest board, I'll just pin some items directly from their etsy shop.