Well the weirdest thing happened recently.... ever since my camping trip (see post in Open Discussion "Who says a Mercedes can't off-road?") the squeeking noise disappeared, all together... have not heard it since. Though the steering wheel vibration was still there, so today (3 days after camping), I had the tires rotated, well that cured the vibration completely. So the steering wheel vibration was caused by the tires, and the squeaking? Geez, I have no clue.
The car did get VERY dirty (for pix see post!) with tons of mud and the like. But I washed and sprayed everything thoroughly the day I got back. I then, on Tuesday, took the car to the self-car wash, and sprayed all the crevices, the wheel wells, and underside of the car thoroughly to rid what mud/dirt was still stuck.
Well, I guess my problem is solved (*knock on wood* ZEBRANO of course!). Thanks for everyone's help, I truly appreciate it.

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2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)