We hire actors all the time. There are some issues. Your IRS declared many years ago that performers can never be contractors; they are always someone's employee. Actors with a lot of independent work often create a "for service only" company to satisfy this requirement. We use a paymaster as the "employer of record" so we don't have to deal with all that paperwork. The paymaster takes care of state workers insurance as well.
Next is the union or non-union issue. If the performer is not in a union, just have the actor sign a 'talent release' that specifies how you can use the performance and for how long. We have a general release that gives us the performance "for anything" and "forever."
If you hire a union performer, you'll sign a contract that will specify the actor's salary, how the performance will be used, and for how long. A union production involves a lot more paperwork, and will probably be more expensive. If you are casting through a talent agency, they can answer most of your questions about union requirements, or you can visit the union's website.
One caveat, if your talent agency offers to send you an invoice, make sure they are acting as the employer of record. If they are not reporting & witholding taxes, you could be liable for back taxes in case of an audit.
Having said all this, I know that small independent productions do their hiring in other ways that I can't comment about.
I hope this is helpful.
American Heart Association