if you register a company in free zone you don't need local but if you register in dubai downtown etc you need local to register a company.

there is no business visa exsist i think only you will have invesitor visa if you register company either in free zone or with local partner

To do business you need invesitor visa to live you need residant visa and to work you need employment visa its up to you what visa you need

Note free zone means limited boudries you cannot go out from free zone otherwise you have to pay tax or something fee etc i dont no exact to enter your services in dubai downtown