I mean that sort of thing is pretty much standard operating procedure for any forum. Whenever you ban anyone the first thing they'll do is make a new account. Keeping out the spammers and whatnot is hard enough without return customers.
I think messages from other iphones show up as green, with messages from android phones showing up as blue. No clue how this interacts with group chats.
Gotta be careful about some sweeteners too. Xylitol is pretty toxic to dogs if I recall correctly.