Your credit score needs to stay relatively the same from application to closing. 

The 14 day trial requires your credit card information.

Also, I have heard success stories of folks finding good contractors at the home improvement stores early in the AM.

You are required to contribute towards these improvements.2.

I suspect the builder has crappy credit and can't get approved on their own.Also, as a former banker myself, local banks aren't generally interested in financing new construction on this size of project or a builder that doesn't have extensive experience in these type of builds, in my opinion. 

The bank will want you to be working for a certain amount of time and that have certain credit score plus have your financial ratios match what they want. 

When I look for my next property, I work on cleaning up credit, so my scores are as good as I can get them.  

Average maintenance and capital improvement: 350/month (4-5kyr).

We're wondering about various what-if's though, such as what if the people tear up the place, what if we don't want to rent to someone in particular due to references or credit or pets, etc.

Credit agencies ding you for having a statement balance.