During the scheduling phase of September 18th you can easily change the teams available to play against, but can you change whether or not the game is home or away? If so how?

Even when I tell the AD to schedule a bunch of easy teams at home it does not always work out that way, maybe since I am trying to build up a weak team it impacts who will visit.

No you can't. Yes, if you have a weak team, often the AD is unable to schedule many home games.