yes its normal to spill oil out of the exhaust
how much depends on how rich you are running the engine, and what brand of fuel you use.
When I ran Traxxas Top fuel for example I had tons of oil coming out of the exhaust to the point you could see where I ran the RC as there were lines going all over. Swapped to o'donnel, and had way less to where it wasn't noticeable


as for brakes... yes some aren't that strong it all depends on the brake style, how adjustable they are, and how powerful the servo is that is engaging them. I'll be honest I never saw one that pushed on the bell housing before.