Whether that is most contractors, hiring an engineer, or getting self-educated.

If finding a new replacement is more difficult then get your new property under contract first even before your old property closes.  

My only add is to the replace your wife's income part.

Imagine investing in all new, beautiful finishes, only to discover that the drain pipes are faulty and need to be replaced—an issue that could have been identified and addressed beforehand.

If they've collapsed, they will need to be dug up and replaced.

Financial independence requires more than just replacing your current income.

However, I wouldn't necessarily recommend full replacements of any or all of them. 

One golden rule I follow,if it takes a long time to fix/replace when it breaks, don't buy a cheap one.Imagine, this thing breaks in the middle of your peak season and the people who can come out to rebuild are 2 weeks out....It takes at least a day or two to build something like this even if you are super skilled.

We plan on replacing the flooring and possibly new kitchen countertops. 

A replacement has not yet been identified.