It's nice to see someone do this. I write my own contracts, starting from an oral negotiation. A tool like this provides a nice framework for such a negotiation.
Clause 5 is phrased clumsily, perhaps:
"Upon complete payment, the Contractor licenses the Commissioner to reproduce and sell work or assets created for the Project, only as incorporated into the Project."
- that could avoid controversy over whether the rights are being *granted* or *licensed*. It's "clear from context" that you mean "license," but it's good to have all the language consistent with your intent.