Newbie, few 4.8is questions...

[B-A-R]

Hey there gang...

New to the forum, just wanted to say hello and tell you all i've like this site a lot, very informative!!
I just picked up a 2004 X5 4.8is, and had a few questions...

Engine braking! The ONLY thing about this ride i cant stand! Anyone explored any possible bypass? What is its purpose other than sending passengers heads lunging forward at slow stops?? Uggg....
Lighting: Read a prievious post regarding an HID retrofit for foglights. Ive done this in my 03 Dodge Ram, but the kit i used STRONGLY insisted the load the new HID ballast's and ignitors would melt the stock harness, and supplied a seperate power lead directly to the battery. The mod shown here is plug in and play, just wondering if anyones noticed any problems using the OEM harness?? I suppose contacting the maker of that kit would answer the question, but thought i'd pick your collective brains as well....
Winter tires..
Not many options (TWO!?!?) for these massive 20's. Anyone had any luck with The Dunlop or Conti's winter offerings for 20's?? I've read alot of you are getting a backup set of 19's or 18's, just worried about the big brakes on the 4.8 might have clearence probs with OEM bmw 19's...

Any thoughts appreciated!!

-B