As a nanny I have never been live-in. I commute to work daily. This means that families I have worked for have lived within a 30 minute drive. My working day is typically 7.30-7.30 so I don't want too long a commute on top of that.
Salary will vary. You need to work out what you can afford and then start by offering below that, so there is room for a rise over the years.
As an employer you pay Employers NI on top of the Gross salary you agree with you nanny. Many nannies talk in Net pay terms (the amount they take home). There are Net to Gross Calculators and Tax Tables which can help with getting a feel for the calculations but you won't know for sure as the nannies taxcode can vary. Thus it is useful to have the Gross salary in the contract if you possibly can.
Nannies salaries vary, with city locations usually being higher than rural. Looking at nanny jobs in your area can sometimes help give an idea as it shows what other jobs are offering, though not all will provide salary detail.
What sort of things do you want your nanny to do?
Some nannies will do quite a lot of household chores and others will refuse to do any, so you need to decide what it is you require.
A list of some things I do/would do:
taking them to/from school/pre-school
taking them to after-school activities (such as Rainbows, Beavers, Swimming Lessons, Ballet Lessons),
taking them on outings such as to museums, woodland, general swimming, playgrounds, gymnastics/playgym, historic houses, on a bus, on a train, on a boat, on a plane/helicopter (that one may not move!)
taking them to groups such as toddler group, music group
care of pets
children's clothes laundry (wash, dry, fold)
children's bedding laundry (wash, dry, fold)
I have been known to iron a school shirt - school/individual photo day!
general vac around the house
general tidy around the house
sorting Lego in to boxes
Have never worked in a home with concealed cameras. It is not a good way of showing your nanny that your trust them. Get them to send you photos, keep a mileage log (if using their own car this is a requirement as you will be reimbursing mileage based on the log), you may want a diary kept. Have a good method of communication between you that works for you both - I have found that email and digital calendars can work very well, though are not fool proof. Text messages can be useful at times but connectivity can be a problem (I work in Surrey near the M25, yet still fail to get a mobile signal a lot of the time when at work).