R.B.
we just used a "real" babysitter for the first time ever last week. she is licensed and her rates are $2.50 for the first child and $1.50 for every child added. she is licensed, your sitter is younger then i would say drop the .50 off both children. as far as how she is going to get to your house and home, i would ask her and her parents how they would like to handle it.
good luck! on tuesday when it was the first time having someone other than my mom watching the kids i was so worried all day (even thou i trust the lady and have knowen her for almost 15 years) just about the little things i know they like and thier routine. all fears quickly left when i walked in and my son gave me a BIG hug and then went over to play with the other child there.