Don't put tall ass tires in an attempt to correct the 4.10 gearing, thats a ghetto ass redneck fix. Keep your 255/55/18 or at least the proper rolling aspect ratio diameter. Save your transfer case and your speedometer for that matter.
If you want to get rid of the 4.10 gearing, just get a 4.4 front and rear differential as they will bolt right in to your manual X, and enjoy 3.64 gear ratios. They are readily available on junked X5's, on ebay etc. Change the driveline fluids afterwards as well, with Redline 75W-90 gear oil in the diffs and proper Xdrive fluid in the transfer case.
For weatherstrip clamos your welcome:
BMW E53 X5 M54 3.0L Search SiteSearch Weatherstrip - 51717006757 - Weatherstrip Mounting Clip - ES#128467
And yes if you ghetto rigged your CCV system and have a broken valve cover hose you are losing oil out of it. Take off the catch can, replace your CCV with updated cold weather parts and the cold climate dipstick tube according to this PDF, and your X should run proper again, with no oil consumption:
http://chrisparente.com/Images/530/CCV-SIB110803.pdf
Idling rough and then dies, I wouldn't think that is condensation in the MAF at all. Probably your vaccuum leak is making the idle rough (again, fix your CCV system properly and remove ghetto catch can fix), I would also check your spark plugs at 122k, your DISA valve, and your lower intake elbow as they do crack and cause vaccuum leaks.
Wipers I can't help you with but the rest I hope I did. Welcome and I hope you follow the suggestions to fix the X5 properly!