On page 117 of Brandon Turner's "The Book on Rental Property Investing" he has a chart to calculate capex and I did my best to recreate this with more accurate prices (in the book he only budgets $5000 to replace a roof).

However, there's enough risk that many insurance providers are requiring replacement. 

What you may save in material you will make up for in engineering and architecture fees. 

And then as part of the land business, I saw an opportunity to go into new construction in eastern tennessee area with the vision of building some to sell and building some to hold - to where I could replace all the equity I gave up when I sold about half of my rentals here in Illinois.So now I'm sitting on a hefty pile of cash.

We could have replaced it that day for $700.  

If there are items you need to replace and they are less than $2,500, you can take advantage of the de minimis safe harbor election, which allows you to deduct those costs in the current year rather than capitalizing them.

They expect us to replace lightbulbs, won't change furnace filters and we also have lawn maintenance issues with them.

Before contracting on the lot, you should check with the local municipality to verify building requirements, current code requirements, list of required documents, surveys, soil tests, engineered plans, etc.Once you have identified your lot and finalized your estimate its time to build.You or your GC will get the permits.For the final build, there are 2 ways to build, as either a cost plus, or fixed price project.Hope this helps, let me know if you have additional questions.

I have found another property of interest and I am considering selling the replacement property from this previous 1031 and using it to 1031 into this new property.

Yeah - if you think about it, the cost of replacement is the cost of replacement, regardless.