for the fuel gauge, its most likely the sending unit in the tank... common issue.... the gauge tends to not read the proper amount of gas, or sometimes drops to "E" even if the tank is full. The A/C can be done pretty much anywhere... just look around for places that specifically test and recharge the A/C... try to look for a nicer shop too so you can be sure their equipment is good. Tune up parts can be had at autozone or another auto parts store... price is MUCH more reasonable, quality is the same and usually there is a lifetime warranty. As long as the car is and always was taken pretty well care of, like oil changes and other routine matenience, you'll get at least another 100kmi out of it!