After losing my son and his mom, I realized that my time with him was cut even shorter because I had to spend most of my time at a job that I didn't even like.

You can have an attorney draw up some kind of partnership agreement, but that also cuts your ROI and increases your expenses potentially for tax advise. 

I guarantee you can find a younger, more upstart builder in your market who would be over the moon to have a PARTNER in things to pump up volume in a rapid sense, and would cut a far better deal.

My issue is that we are finally through planning and I am at my last step before construction which is obtaining a curb cut permit from NHDOT.

However, lately I have been seeing appraisals come in lower than anticipated so be prepared for a value cut (Subject to your market of course)Lastly, you can do a delayed purchase and use 100% of the initial cost so as long as the loan amount does not exceed 75% of the new appraised value.

Could someone either give me an estimate of average lifecycle for common components of a house within Florida, or recommend any local contractors that could give me an affordable inspection report?

If you are just starting out, get your finances in good shape because it's likely going to be death by a thousand cuts getting a property to market. 

If you don't want to get your lenders in trouble, pick up a copy of Lend to Live in the BP bookstore for both of you to educate yourself on how to do it the proper way so that it's a true business transaction and not cutting corners just because you know each other personally. 

If this is a refinance, a lot of lenders are looking at values more closely and will either agree with the appraised value, require a secondary report, or just cut the value all together. 

Then, if you could cut 30" out of the top elevation you would be in compliance.