I just recently took my passenger door panel off. Now I am not sure that this "aftermarket" shell is the same as the original, but it is similar (as I haven't seen the original door panel on drivers side in a long time, the inside of the panel, I mean).
I was checking it out, and it did not look like the wood can easily be removed. Looked like there were permanent "clamps" or something of the sort. But if the wood does not need to go back in, they I wouldn't worry about it. Your best bet is to take of the door panel and see for yourself, then experiment.
As for the armrest, I can't be sure. I know the top of the armrest (top of the handle) is unscrewed when you take the door panel off (through the screw behind the plastic panel behind the door handle. I believe the other end of it, armrest area, is similar to the wood, but can't be sure.
As for the hose, I say go for it. If you can see both ends of it, and get the right hose and connectors and tools, and you are somehwat mechanically inclined, I'd say for for it. Why not change the fluid and filter why you are in there? If you need help on that, just say so, I did it successfully with relative ease.
I think you would still have enough room to change the bulbs without removing the steering wheel? But I am not sure, why don't you try it out to be sure.
As for the grease, do you mean mean for the wiper arm? I just used a teflon spray. I think any ordinary lubrication will do the trick. But you are probably better off getting a real grease if you want it last some time.
Good luck and let me know how it goes!
2006 E350 w/ 155k miles (Daily Driver)
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!)