A friend of mine has two service stations in peshawar. He told me a lift/jack costs around 2 lacs each. I think service stations usually have two due to lack of space, otherwise i don't think there's a limit on it. If he's planning on opening one in islamabad he'll need permission from CDA.
The cleaning guys will probably be on fixed salary, that's up to you how much you can convince them to work for you. As for land i think you would need at least 2 kanals to give ample space for jacks, waiting areas, parking etc.