I am currently a PetSmart groomer. I have been there for 6 and a half years. I hope I can answer your questions to the best of my knowledge, at least with my store.
1. They say we are not allowed to participate in outside grooming while UNDER contract. Don't quote me on that, but I'm pretty sure.
2. In our salon we do not have the room for extra pets to be there. Atleast not sitting by our tables. However, you do get to bring in your pet if you have somewhere they cane be. Of course you do get to bring your dog in and groom while at work once a month. My dog comes with me when she has vet visits and needs a bath.
3. Our store has mostly full time groomers. We are scheduled 40 hours for the most part. But, being full time you are required to work atleast and average of 36 hours. If you did want to be part time they do offer that, morning, afternoon and evening shifts. I am sure your Salon Manager or Store Manager would be willing to work with you.
4. Most PetSmarts will require you to take what is called a "technical". This is where you pretty much show that you have some knowledge of breed specifications and what not. If you are accredited elsewhere and have a nice portfolio to prove what you can do on top of the "technical" I think you would be okay.
5. I do not hand strip. We only have one girl that does it in our salon and she only does it with certain restrictions. (ie pricing, timing, etc)
6.We are required to wear mostly black, what I like to call "parachute pants". They dry quickly and if they are made of the right material hair does not stick to them. And of course we have to wear the provided PetSmart black smocks. And I find that wearing black rubber water boots keep my feet nice and dry.
Hope this helps and answers your questions. Now some stores I'm sure will be different. But those are great questions to ask in interviews. =D