How much is insurance, heating and electricity?
When was the last safety check performed?
How is the structural integrity of the building?
Are you going to commission a structural survey?
What are the business taxes on the property?
Have you factored in employee costs?

What is the size of the theatre? Have you checked to see if your $2000 projector can fill the space?
What sound system are you going to use?

Have you considered how you will be able to legally show movies? Have you considered the work involved regarding licensing? Have you factored anything towards advertising?

How will the theatre business be set up for tax purposes?

Why did the theatre go out of business? If it was a loss making concern, what are you going to do different to cover those losses?