Regarding funding, it isn't quite as simple as saying they won't get any help from the LA.
The LA receive money from the government to fund schools in their area. The LA deducts some of this to provide central services, regardless of whether or not the schools actually want these services or feel they are getting value for money from the LA.
Academies are funded direct from the government. The school gets more funding but doesn't get some of the services from the LA that normal schools do. However, the LA still receives funding for some central services including educational psychiatric services and SEN assessments. The LA is free to offer other services to academies in return for a fee. If the academy wants the service and feels the price is reasonable it can pay.
Academies can set their own pay rates, so they can pay teachers more or less than they would get in LA schools. They also have more freedom regarding the curriculum.
Academies set their own admission criteria, although the rules are fairly restrictive in terms of what they can actually do - they cannot, for example, become selective schools unless they are already selective prior to conversion.
The new academies are largely the same as the existing ones created under the last government but they no longer need an external sponsor.