Hi pendemic, welcome to AF!
1. Do you mean the multifunction switch in the steering column (the lever that controls the wipers, turn signals, and high beams)?
2. Do you have any idea where the rattling is coming from? The engine compartment? One of the wheel hubs, perhaps?
3. That is the E-brake cable but I'm not sure how to tighten it up, unfortunately.
4. I'd suspect you will have to access that from the inside of the door. The only stuff I've done with the door interior off was replace a speaker in one of these cars.
5. Sounds like it needs a good tune-up. Since you just bought it, you probably don't know what much of the previous maintenance on it is. So you might as well cover your bases. Change fuel and air filters, replace spark plugs and plug wires if necessary. Clean your MAF sensor using CRC MAF Cleaner spray and disconnect your battery for atleast 15 minutes to reset the computer. Check for proper operation and timing of the distributors. Change your oil, ATF, coolant, and power steering - at the very least, check for proper color and odor.
If it still has that problem, it may be old/bad gas, a sticking Idle Air Control valve, or a weak fuel pump.