You can't depend on a resume. The building(s) that the potential new hire was working in before may have nothing in common with your building. In general, the older the building the smarter and more creative the maintenance person has to be. There aren't a lot of replacement parts for something made in the 1940's. He/she will have to Make-do and improvise. That's not going to show up on a resume. Don't look for a "Team" player, maintenance people spend the vast majority of their time alone.
The maintenance person is the face of your company that the tenants most often see. Management is something that they would rather not deal with and just gets in the way. Most of them are mad at the office for promising or seeming to promise something at lease signing that was never delivered, or about an evil clause that was buried somewhere in the gigantic lease document that a leasing consultant "Walked them through" rather than allowing them to read. Anyway, they likely feel cheated. Well they do! They need a maintenance person that they can like, not necessarily one that you like.
If you have a new and well built apartment complex (I saw that in a dream once) you may have very specific needs and only those needs. In that case you might be well off with a "dim bulb" type person who can paint and pick up around the dumpsters. Anything outside of those parameters you'll need to call a vendor. If that's what is needed, then that's what you should hire. A "dim bulb" person will be happy with any job and not aspire further, guaranteeing longevity in the job.
If you need a non-"dim bulb" person, forget the resume. Ask them about their hobbies. They should have artistic and scientific interests if you need a go-to guy/gal. A few basic plumbing questions such as "In general what is the minimum slope of a waste pipe?" or "Could you compare and contrast traditional copper soldering with Shark-Bite type fittings?" If that doesn't throw him/her for a loop then he/she probably knows his/her stuff.
As for electrical knowledge, that seems to have been taken out of the hands of maintenance. Check with your own jurisdiction. In my home state of Washington, it seems that maintenance people working for third party managements are not allowed to touch wires. Replacing a fifty five cent light switch now calls for a licensed electrician at huge expense. If you live in a less stupid state, you might ask the potential employee why you shouldn't use the push connectors on the back of the switch or receptacle.
How do you keep a maintenance person? A little respect wouldn't hurt. Recognize that they are not the Genie of the lamp at your command but people with limitations. As a manager, think it through first. Don't insist that they do something that is obviously stupid. E.g. Ask them put in a bed of beauty-bark in a desert area that has 70 mph winds. Don't treat them like an easily replaceable cog in a machine. It takes a long time to acquire the many skill sets in the many trades necessary to their job. Acknowledge their value. Mention the outstanding job that they are doing to upper management. Offer job incentives such as possible promotion into management after 3 years of service or the like. An unexpected little bonus for service above and beyond might be a good thing.