Rocky - the cleanser is just rubbing alcohol, to remove any oil from your nails pre manicure, and also to remove the slightly sticky finish you get at the end. The polish remover is, something like, 93% acetone w eucalyptus oil and something else, so they are definitely different things.
I like the kit, but I had never had a gel manicure in a salon, so can't compare it to any other products.
I've read that you can definitely use other products with it, and I've used OPI gel as well as SensatioNail polishes.
My manicures definitely peel if I don't use the primer, at least around the edges of my nail. However, with primer, they last well, for me. Normal polish just chips and peels on me.
I do a light buff (to break the topcoat seal) and apply more polish and topcoat after a week, as my nails grow quickly and I don't like regrowth. It's faster and easier than taking all the polish off and starting again.