TANK

hi everyone im just about to complete the sale of my 450bhp impreza and with the funds i am seriously considering an x5 im a little worried about a few things though if somebody could point me in the right direction ive read of auto-box failures, if this happens what sort of cost am i looking at to get it fixed and where is the best place to go? also the air suspension ive heard car be very costly to fix, is there a spring conversion that can be done? the version i would like is a 4.6 v8 facelift, are these generally reliable? i cover around 5k a year and i will not be off-roading in it, i know these engines have a timing chain,does it need replacing or is it a life-long chain? are there any specialists that can do all the work mentioned? i will not be using the main-dealers cheers everyone matt