United Food and Grocery Workers (UFCW)
The grocery store in Twilight is called Thriftway. :)
Probably not, though you should consult your lawyer (if you're opening a grocery store, you should have one already; just ask him).
You can buy apple cider vinegar by exchanging it for money at a grocery store. You can ask the grocery store workers for help finding the product if you need it.
A market or a grocery store.
thriftway
Commissary.
They are most commonly called aisles.
walmart i know because my grandma works there and they give you a discounts and are happy workers
perishables
you can get a workers permit from your school when you turn 15, but it is only good for certain businesses.
The brand name was Mel's but I don't think you can find it at a grocery store, but I'm not really sure.