How many times you see someone with disc brakes loop out?Now how many times you see someone going to bashplate after failed bunnyhop/gap?I´m yet to see someone with hope brake to loop out, but I see them landing on the bashring every ride because the brake just isn´t able to lock that amount of force...It´s basic stuff and you will get that as soon as you start going bigger(Or gain some size).
Exactly opposite, so wheel is more likely to spin backwards than forwards, hence the rotor should be mounted other way round as front rotor, where 90% of forces is trying to spin wheel forwards.