If pre killed or f/t isn't working, throw a live mouse in after you change your set ups. It's more important to get the animal eating than worrying about whether it is pre killed or f/t.
Like the previous poster said:
10 gallon
You can put more than 2 hides in, mine has two small hides on the left of the tank in both corners, one in the bottom right corner, and the water dish is in the top right hand corner.
You can put fake plants in to help fill the space.