X5 4.6is Brakes question and other questions and code info

[BiiQ X5]

Hey, just want information on these things that have popped up lately. I had the car sitting for about 2 years without constantly using it and when I did restart it again I noticed the brake reservoir was empty. Brake pedal went all the way down.

I filled up the reservoir and still the pedal goes all the way down. Now the fluid hasn't drained down and it's been like 4 days since I filled it so if that's the case. What can be the reason for that? My guess is that it has air in the system and I just need to bleed it. Maybe it can be the master cylinder? Need some advice on that.

Also, when I change the auto gear to reverse or drive I feel the whole car like go back and forth, kind of like after you press the brakes and the car wiggles foward and back and feels springy.. not sure of the transmission change can even impact the springs.. can they?

Also the codes that I got with my peake reader

Code E0 msr intervention plausibility??
Code 66 mfl interface??
Code 0f precat o2 sensor slow response (this one is obvious) I will change the sensor.