2002 Jetta whobbly noise and needed parts

[cesario1212]

Quick Q for those that can help. Any help would be very much appreciated, especially on starred Q's.

*1. When I drive my Jetta 2002 GLS 1.8T 5-speed manual between 20-45 mph, I hear a weird "whobbly," deep resonate/bass whoom-ish sound from either the passenger rear or passenger front...I can't quite pin point it. Anway, I took a fellow VW owner for a ride and he thinks it's a tire balance issue of some sort. I made clear mention of this to the dealer when I took it back in for the scheduled safety inspection ( I just bought the car used) but the sound is still there. It's terribly annoying. Does anyone have a clue as to what the problem may be?

*2. My coolant levels are above the prescribed markers. I read the manual and they made no warnings about it being over, but do I need to get rid of the "excess" coolant. The dealer just left it in after inspection. I know how finiky the manual was about other fluid levels, is the coolant the same way, or can I just leave the "excess" in?

*3. I think I have the anti-theft bolts on the aluminum wheels. I'm missing four of the solid black caps that cover them. Does anyone know where to find them cheap?

*4. Anyone know where to get a single floor mat lock to replace the one I'm missing on the front passenger side?

5. Anyone know where I can get a extra key made (wallet size) to use as a spare when my other "bigger" keys are forlorn....(yes forlorn because I can't think of something else that isn't as silly)? Some place cheaper than the dealer?

6. Do I really need to worry about the engine coils?

7. Can I not replace the battery myself without having restart problems for the car due to silly computer chips losing power? I'd rather avoid dealer fees and having to buy special equipment.

8. Does anyone really wash their alluminum wheels as often as the manual says to (once a week)? Seems silly, expensive, and a waste of time for something better. Especially in cold weather.

Art-man