L.F.
I was a live-in nanny for 4 years to one family in my late 20's and early 30's. I went through a nanny agency in Boston and they had the parameters set up before both family and perspective nanny were even hired. Anything outside thier requirements were terms of negotiation during the hiring process.
As a nanny I was required to do anything around the care of the child(ren). That meant anything from kid's laundry, kid's meal preparation, playdate appts, house cleaning of kid's room/play room, etc. Please remember that a Nanny is not the same as a housekeeper. It's a touchy thing to always remember. While many of the responsibilities may cross over, a Nanny is not there to do housecleaning while the baby is sleeping. However, I do know of some Nannies that negotiated light house keeping. i.e. vacuuming, dusting, picking up, parent's laundry, etc. for an additional fee. A 4 mos. old gives a nanny a lot of down time b/c of sleep schedule. If the nanny was responsibile for a toddler it might be different. It might be worth the extra money to have her do a little more cleaning, for an added fee, to free up your time with your baby when you are not working outside the house.
I was given all meals while I was working and had access to anything in the kitchen. If there is something that is set aside for a special occasion I would ask her not to eat it but otherwise, it's fair game.