I'm hoping someone has run into these minor problems and can help me out - with advice...and/or tell me if this is common.

I purchased my second volvo 2 1/2 months ago after having a positive experience with my first, a 1988 volvo 240DL.
I purchased a 1999 Volvo S80 with only 60k miles on it, from a dealer in Florida. The car was a lease vehicle, then returned, then went out again as a certified pre-owned lease vehicle, then went to a certified lease dealer auction where it was purchased by the dealer that I bought it from. So, technically, I'm the 4th owner, but the dealer that bought it from the auction didn't have it more than a month. I've put 3k miles on it, with one long distance, 1k mile trip in the mix. As soon as I bought it and it was delivered, I noted that the emissions msg was on and that the low coolant was on. I filled the reservoir, the coolant message went away. I took it to my local Volvo dealer to have it inspected and a used car inspection done on it- and they found it to be in "excellent" condition other than a few minor cosmetic issues, like the drivers window will stick ocassionally and I should replace the regulator, and ocasssionally the rear passenger door lock will not unlock using the remote. They fixed the emissions problem, passed it for the inspection, and told me I had purchased a "great pre-owned Volvo", $500 later and that wasn't fixing any of the cosmetic stuff.

In the last 2 1/2 months, and starting within 2 weeks of owning it, the following things have happened:
6 weeks after the low coolant light came on - it came on again. The reservoir was low again, so I filled it and the light went off. It remains off now, but another 6 weeks hasn't passed yet.
The lid to the fuel tank popped off in my hands. I am assuming that maybe the connectors got fried from the Florida sun, and at $9.95 to replace the hinge, I'm not too worried about that, just dismayed that it happened.
When you run the air conditioner, heat or the front defrost, after a few minutes, the steering wheel starts to vibrate and if you keep running it, eventually it starts to make a roaring noise, that can only really be heard from inside the car. I've been told theres a recall on the fan, but I'm not sure if its the fan.
If you turn the wheel sharp in either direction, randomly, it will make a "bark" like noise.
If you accelerate too rapidly up a hill, there is a knock and a rattle that almost sounds like its coming from the trunk. I've been told that possibly thats only an exhaust mount- but as the list continues to grow, I'm almost afraid to ask.
Sometimes, when you take the key out of the ignition, the car continues to "beep" as if you've left the key in the ignition. If you ignore it and then try to lock the car, it won't lock. You have to get back in the car, re-engage the key, take it out, make sure its not beeping, and then it will lock the doors.
And the biggest cause for concern- I'll do my best to describe this...when you accelerate up a hill - and it gets between 3-5 RPMS (35-45 mph), it makes a whining noise. Once it downshifts, the noise stops, but if you accelerate again, it makes the whining noise. Its not exactly a whine, but its very hard to describe the noise. I've had a couple people in the car who said it sounds like possibly a vacuum hose.
This is coupled with the fact that, in my opinion, it is the noisiest engine I've ever heard, especially in what one would expect to have in a volvo. Its not that it knocks, but it makesa ringing noise.

Any help before I send this car off without a clue to the volvo mechanic? And while I'm at it- the pros and cons of sending this car to a Volvo mechanic versus my regular mechanic?

ADDED: - the car does drive like a dream and does virtually float on air, other than a little too "floaty" in the steering for my likes- and its been very reliable other than these minor things that keep happening and the noises. Is this common in the 99 S80? Its routinely getting 26 mpg with heavier city driving - but it does often seem to be a little sluggish and sometimes will seem to hesitate. It goes to 40 with no problem, but getting it from 40-60 seems like quite a chore. It is not a turbo.

Thanks