You can never charge lipos inside your robot- even if you have a lipo bag inside.
I would definatly no use a botbitz 10A for 15A motors (I presume for a feather weight)- using the 25A ones would probably be alright but is a bit risky, the 85A would definatly be fine. I am am pretty sure those ratings are a bit optimistic and that they are the stall ratings rather than continuous ratings.