At the point you are, I'd say you need a few cans of DeOxit 5 and DeOxit 100, and maybe a gallon of Evap O Rust. When I got my car, I just started going through the engine bay to clean, and if I saw an electrical connector, I unplugged it to look inside, then give a shot of DeOxit 5 or 100 ( as needed) and reconnect. Eventually, I had a day (weekend) when I got to do the taillights, and running lights, another weekend for the gauges, etc. I prioritized the cleaning in order to get it safe enough to drive around in the day, then at night. Lately, I've been going after the connections in the back- fuel level sender, fuel pump, etc. For the heater, I'd suggest checking the vaccum lines to that. My car (Florida car) had to get all the rubber hoses & such replaced immediately because they were all dried out, cracked. leaking vaccuum lines will not help the geater work right. You might also need a coolant system flush (rusty heater water valve inside). It wouldn't hurt to get one. When you say the antenna is broke, what does that mean, it won't go up & down by itself? I just leave mine up.