Every project is fluid and can expand or contract in size. I include a certain number of hours in my estimate, and bill on actual hours.
It is also my experience that new ideas come during the work. These ideas are often so good that the customer does not want to trash them. In those cases, it is a matter of re-allocating production time or adding to the cost.
As a producer, I think that it is important to “manage” the project with the client. I include the name of the person with final approval in my service agreements. This eliminates many of the problems that you listed in #2.
Have a wonderful day!
Well behaved women rarely make history.
Karla Patterson
Video 7 Production Co., Inc.
http://www.Video7Pro.com