If you don't already have one, get a Bentley repair manual. It is full of great information that can help you fix your car yourself, or at least be informed when talking to a mechanic.

1) As Greg said, you can read the SRS codes and go from there. Our FAQ here on the board has the procedure, as well as a lot of other information: http://www.brickboard.com/FAQ/700-900/ElectricalSRS.htm#SRSOnboardDiagnosticCodesPre1992. I believe the snippet from Jeffrey Davis is the information you want.

2) You've probably got two different problems occurring there. One, it sounds like the suspension in well worn, meaning shocks, struts, and bushings, and maybe engine mounts.

The kick when shifting from 1st to 2nd is probably a transmission issue, either a worn check ball in the valve body (meaning it will be beyond the average DIYer to repair) or a sticky kickdown cable, but that is less likely. You can possibly solve the hard shift by changing the transmission fluid. I recommend draining the transmission pan into a clean tub, marking the level of the old fluid with a Sharpie, then putting the same amount of fluid back in. I also like the Lucas TransFix product you can find at every Autozone and Advance Auto. I think it helps quite a bit to prevent slipping and clean filth out of a very old transmission. If you decide to replace fluid like this, do it a few times, driving for a while between changes.

3) The first step to diagnosing a running complaint is to know the condition of your ignition components. That is, spark plugs, ignition wires, distributor cap and rotor. Except for the wires, these common wear items are very cheap to replace, and many of us do this the second we acquire a "new" car. From there, you can do things like clean the throttle body and Idle Air Control valve, and look for any tears in the plastic accordion hose, or vacuum hoses.

4)Could be a lot of things, but most often, an unbalanced tire.

The "whooshing" sound behind the dash you mention could be a vacuum leak in the cabin air controls. Do all of your controls seem to work? If you push in the button for recirculate, does the sound go away? If you push the defrost or floor button in, does the air appear to redirect? It's just a possibility; not the only one.

Good luck sorting out the problems. It usually takes me a good bit of money and time after acquiring even a well-preserved 240 to sort out the issues that the previous owner gradually let build up.