For problem #1: Base your billing on your costs for labor, amortization of hidden expenses — e.g., insurance, vehicle costs, depreciated value of equipment, etc. — and profit. I recommend you calculate your charges on time. For example, actual shooting and editing time, time spent on site location, story-boarding, travel, etc. If you bill this way you will bill high on complex jobs, less high on small, easily done jobs.
You are “selling” your time and talent to a client. The value of your talent may be debatable: a client either appreciates it or not. But the time you spend on a project is quantifiable and you can put a dollar value on it.
And this, of course, ties in to your second problem. If you are charging by the hour for editing, your clients understand that changes cost money. There’s no reason why you should absorb the value of time spent making changes.
