AC isn't hard IF you have the right tools. Got a good vacuum pump? Set of manifold gauges? And unless you are going to flush out the entire system to remove the old oil and dirt, converting to R-134 is going to be tricky. I would stay with R-12 if you can get some cheap and if not then there are plenty of R-12 substitutes that work fine. I used "Freeze 12" or something on my Mom's car and it worked great. I myself used ES12 on mine and I am very happy since the original mineral oil is compatible with it. Most of your parts should be good as long as they don't have corrosion holes. The compressor is always the problem so just assume you will need a rebuilt or new one. Also, compressor companies won't warranty a compressor unless you can prove the system was flushed and a proper shop did the work. Wiring is easy, the system is just "on" as long as there is enough pressure on the low side. Same wire that engages the compressor activates the carb solenoid.