Yes the concept is good... however, I would have all the children at a nearby home instead of your home. I would also hire an extra sitter to help her out unless you are spot on sure she will be ok qith 10 children.
As far as pay, around here minimum is $10/hour but for 10 children, I'd pay more.
My daughter is 17 and the last time she babysat 6 kids alone (2 couples, total 6 children and the 2 couples went to a concert in Dallas) she was paid $160 cash. She typically averages $12-$15 per hour because she is good...
Holiday time... (with pre approval from parents) she takes gingerbread houses to decorate or holiday crafts from Pinterest. On regular sitting job, she also takes crafts, helps with homework, teaches Spanish and is very involved with the children.
Yes I think the adults will have a better time if the children are not there.