I'm a freelance artist for MAC.
Free-lance artist perks are that you get to work when you want to, and that you get to work at multiple counters/stores if you have them in your area. You don't get gratis or an employee Pro Card, though. So that stinks!
If you get hired as a permanent part-time then you get the gratis and pro card, and you also get guaranteed hours at the store or counter that you are hired at.
You have to take in your resume and a completed application (get one from the store or counter) and hand it to a manager. They have open calls for hiring artists once every couple months, or maybe every month in your area. You'll go in with another copy of the application and your resume, and dress in all black with your makeup done and they will give you a 5-10 minute verbal interview. If they like you, they'll invite you back for the second interview. The second interview is a group interview where you'll be asked questions about the company, product knowledge, sales knowledge, etc. and then you'll be asked to do makeup on a model (that you will have to provide). Our models got switched when we got there, so we were doing each others models makeup. The ''look'' for the interview is decided by whoever interviews you. Then after you do the makeup they'll talk to the models and then bring you in and say thank you, we'll call you. Then within about a week or so you should know if you have a job or not.
I know some interview processes are different, but that's how mine was. Hope that helps!