Question on rims -- '06 4.4i sport package

[nosoup4u]

I've done some searching and just want to confirm:

a) 17" X5 rims (2000-2006) will fit? I am looking to purchase these for a winter tire setup.

b) with the 17" X5 rim setup - how much will this throw off my speedometer?

c) Will the E83 X3 sport edition rims fit on the X5's? I believe they are non-staggered. So, I would think they have to be ET51 (doubt you can fit 255's on an 18x8 rim). I am confirming.

I currently have the star spoke 132's ET48 front and ET45 rear's. Would have preferred 18's; but, car came with 19's.

With an offset of 51 - it appears I should be able to run these on the front and rear?

Are the hubs different? What about bolt length and size? Can't seem to locate this information on here.

The E83 X3 shows y-spoke style 114's ET46 front ET51 rear.

Thanks

p.s. - just picked up an '06 4.4i with sport, etc. Had an '03 4.6is - but, wanted to get something under warranty. Bought from dealership - CPO'd and I extended maintenance there as well. I have a fairly good relationship with the dealership - can give you price I got and what it started out as - NAV, sport, etc. Have orig. sticker - I think was around $67K or so. I also heavily compared the Chili pepper, CTT, and 05-07 JGC WK's (hemi engine).