Firstly below is a picture of my headunit, (tv, cassette and 6 changer cd with sat nav)

Right after the great switchover there is no more TV available the subscription for the sat nav has expired from the last owner, so my next option is freeview (for the kids), I have a single din Pioneer head unit, which plays dvd, Mp3 and has an ipod control unit and you can also add an additional two screens so my question is,
Can this original Head unit be removed and what will i loose in regards to the controls in the car?
Is there a Single din converter i can buy to replace this unit?
Secondly, I have been reading loads of post on this website about trans fail safe problems, and all cases seem different and on searching the internet I cannot find a definitive solution as everyone seems to resolve the problem differently from as little as £15 for a tin of water repellent to £2000 for a gearbox refurb.
I purchased the car last week and had a ten mile drive home everything perfect no problems, did not drive the car or start it for three days and on starting the car the battery was dead so I then got my RAC jump box which started the car first time. I put the car into drive and it rolled forward and stopped, on giving the car gas it was moving very slowly and as it picked up loads of black smoke came out the back, the message Trans Fail safe appeared on the dash, but after 20 minutes of sluggish driving the problem and the smoke seems to clear and the car drives perfect. This problem only seems to happen from a cold start when the vehicle is left sitting over night but once it warms up the problem goes, but I still get the message Trans fail safe.
Any ideas? The Car is A BMW X5 3.0D Sport Automatic, thanks.