1 amp = how manny volts?

Hello I am having trouble fixing some wiring in my house. I have an older home that has wiring from around 1945. It's that old two prong ungrounded stuff that crumbles when you try to strip it. Anyway, almost all the outlets in my house are ungrounded, and so are the light switches. I have had...

I want to install a chimney free electric fireplace, power requirements are 3,500w. I have 220 in the house, wiil the fireplace work without problems to the electric?

I have 2 refrigeration compressors. One 5 h.p. 480 volts, 3 phase @ 4.5 amps. One 5 h.p. 230 volts 3 phase @ 20 amps. Which one will cost less to run assuming electric costs are same?

I have a set of outlets that the top outlet is controlled by a light switch. They do not work. I get a reading of 79v at all the outlets and at the switch. The bottom outlets all work and read 120v. The breaker controls all of them. Any suggestions