Opening- It depends on how big and well known your home haunt is. It also depends on the schedules of everyone assisting with the haunt. We open and run two days in october. One for trick or treaters and the general public, the other a family night and party.
Admission- We don't charge general admission, but do have a donation box at the end of the haunt. If you are looking to make a small amount of money from the haunt, I would set up a concession stand and some small games for the younger visitors. It has worked the past few years for us, and everyone loves it.
Actors and staff- All of our actors and staff are family and friends. They volunteer their time.
Walls- Other than plastic or material, I am not sure of many effective ways to do walls. You may be able to get pallets for not much, but the hard part is finding storage. Corn stacks and hay/straw bales are also a possibilty.