As for plugging into a regular 120V wall outlet, that is perfectly fine. You can get a full charge from a 120V outlet in about 12 hours. But it is smart that you are having an electrician check things out, especially for older wiring. Plan on replacing the 120V outlet that you will be using to charge since it's likely old and it is relatively inexpensive to replace an outlet. The rest of the electrical system hopefully will be good enough as is. The two important questions that you want to find out from the electrician is:
1. How many amps is the circuit that you will be plugging into. Most likely it is 15 amp, which is why you will most likely be limited to a 12 amp EVSE. There is a chance however that it is a 20 amp circuit, in which case you could use a 16 amp EVSE which will charge slightly faster.
2. What else is on the circuit? Ideally it's a dedicated circuit, i.e. nothing else is on that circuit. More likely however there will be other outlets on the same circuit. A 15 amp circuit can safely handle up to 12 amps continuous power, a 20 amp circuit can handle 16 amps. In either case you will be pretty much maxing out the circuit when you are charging, so it's important to make sure that nothing else on that circuit is being used at the same time that you are charging, or you risk overloading the circuit.
Note that checking the number of amps is something you can do yourself by simply looking at the circuit breaker, although that assumes the correct size circuit breaker was originally installed (or later replaced). It doesn't hurt to have the electrician confirm this, but you can check now yourself just so you have an idea what to expect.
Also it's pretty simple to figure out what else is on the outlet, it's just tedious. But it's actually something everyone should do anyway which is to make a circuit map of their house, rather than just relying on what is written on the panel as that is not detailed enough. To make a circuit map, first identify all outlets, switches and light fixtures in the house (include attic, basement, garage and outdoor outlets) and then draw this out on paper, (i.e. make a map).
Then turn on all lights in the house (and outdoors), then while one person turns off each circuit breaker one at a time, the other person notes on the map which lights that each circuit breaker controls. For outlets you just need to plug a lamp or an electric radio into the outlet. The resulting circuit map is very helpful to have, and it will likely surprise you as one circuit can mix two different rooms that you wouldn't expect.