From what I´ve gathered on different sources including the Mig15bis manual, the airbrake would automatically deploy in the later versions of the mig 15bis (post summer 1952) only below 5000m of altitude. This was where the high speed uncommanded roll was notably dangerous. At high altitude, the mig 15 pilots overcame the issues at high mach numbers using aileron reversal with rudder imputs as curly pointed out, in the same direction of the roll. This is modeled in DCS very well. when you get to mach 0.95 mig starts vibrate heavily just as indicated in the manual and different sources.
I was asking myself this question not along ago, how the hell did mig pilots score kills on sabres if the sabres were above mach 0.9?
As for the spins I´m not so sure either. All of the sources I´ve read on the spins are from western ones mostly regarding the test pilots comments following the mig 15bis defection. I too have the feeling that it is too easy get out of one. On one hand it´s a sim and modeling has limitations. On the other... a lot of simmers spend a lot more hours perfecting out skills than the actual pilots had in real life. After not flying for a couple months came back in the mig and got myself into a nasty spin and wouldn´t have pulled out if i had been at 1000m. So to me it´s probably a combination of the two and I don´t thinkg the mig was that much more dangerous in spins than other aircraft.