At the age of 10 and 12 they are ready to learn some serious flying,check the ama site or if you know of any clubs then check them out.You should be able to find a club with an instructor,and maybe a trainer plane with buddy box they start new pilots with.would not suggest any planes except a trainer w/flat bottom wings at this stage,radio equiment I would wait and see what the local members are using,might buy something that collects dust,and join the ama for sure. Welcome to the hobby/sport,lots of good things.