I would not be happy if my boss set a curfew! However, I'm 47 and don't have a life!! I have never been told what time I have to be home or to call if I decided to stay out. I do let my employers know if I know in advance that I am going to stay out, as they do to me.
Like others say - you are trusting this person to care for your child, you must think that they have common sense, are sensible and trust worthy, I say trust her to come home at a reasonable hour, be fit for work the following day. If she fails to do so, then you can have a chat.
I also don't think there should be house rules as such, your home is going to be her home, have a notepad in the kitchen and ask her to note down things that are running low/out. Tell her that you don't care about the house being a bit of a mess during the day as long as it's how you left it when she finishes work. (One thing I always mention at interview, if you come home unexpectedly, do not expect a pristine house! I'm very firm on children tidying up after themselves but if they want to get every single toy out, that's fine by me but they have to put it all away before tea. I generally batch cook whilst my charge naps, it always seems to take much longer than I expect so sometimes I end up washing up and wiping down while the children have tea. But the house is always tidy (er than they left it!) when they get home. Again just mention, could you make sure the children's (and your) shoes, coats, hats, pens, books are put in the cupboard before you finish, thank you.
Meal times at the weekend - I do the weekly meal plan and Ocado for all of us. So whatever I fancy at the weekend, I just add to it and I cook while they are doing the bedtime/bath time routine so I am out of the way when they need to cook. I do eat lunch out most weekends, my boss tells me to take it out of the kitty so if it's cheap (??7-8) I do, if it's more I pay for it myself. Sometimes I'll say to my bosses in making a chilli/curry/paella do you want some or they'll say we're have a take away do you want to join us? Sometimes they/I say yes, sometimes no, but thanks! I think you have to make her feel at home and as part of the family. But I would also say up front that you don't get a lot of time as a family/couple so we would enjoy some space occasionally!! My boss and I take over the couch on a Wednesday night for GBBO (if I'm not out gambling at the races!!!) and she's trying to convince me various Saturday night shows are great so it's two against DB but I'm with DB, take me out, strictly, X factor - No!!
I have always been allowed to have friends/boyfriends over, my bosses trust me and my judgement but I do think you can say no guests you have only just met (ie one night stands!)