What plugs would you recommend? How much do just the plugs and wires cost?
Loads of options on the plugs. A bunch of went for the Champion Double Platinum #7570. More expensive (about $7 each) but last a long time. Normal plugs will run about $2 each. Decent wires will run about $40-60. Most of us use www.RaceandStreet.com for parts.
I was also thinking about switching to synthetic oil as well. Will this help anything?
If your strapped for money, Synthetic oil will cost 2 to 3 times the amount of regular Dino oil, but you can go further between oil changes. Synthetic oil should also help in gas mileage by 1-2 miles per gallon.
The squeeking sounds as if it is a fan belt or timing belt. Are those easily tightened?
Timing belts don't squeek, they slip and you'd notice a big drop in performance and driving capabilities. There is no fan belt. Fan is electronically controlled. The other belts consists of a small belt for the alternator and a drive belt for everything else. The drive belt has it's own tensioner, no adjustments. Belts aren't easy to get too and even from underneath the car you can only see a couple inches of the belt. Inside passenger wheel well cover needs to come off for access to the belts. Wait till your brother gets out of the hospital.