I will always look at the air handler and make sure tenants are installing fresh filters (most neglect this item).  

Wiring for special purpose equipment would be like having to install 250V wiring to run a commercial walk-in freezer. 

To minimize capital gains tax on the sale of their primary residence, your in-laws can utilize the $500,000 capital gains exclusion, potentially explore an installment sale to spread tax liability over several years, or consider converting the property into a rental to use a 1031 exchange for tax deferral eventually.

We pay $850 for a WH install, so, that seems high but you are in CA.

They can install more control features in $20 and $100 bills like other countries.  

Estimated cost for remaining changes (all new electric, drywall, tile, fixtures, cabinets, roof, doors, windows, heat pump, some siding, and fencing.

Quote from @Alan Mills: Got an inspection objection back with something I’ve not seen on my other rehab’s (this is a Colorado property):“The seller agrees to have a licensed plumber install external sewer cleanouts per city code and scope the sewer line ensuring its integrity.”This was a full interior/gut rehab and almost everything is brand new.

If the lines are aluminum, we ALWAY replace that like we replace lead paint or lead pipes and asbestos ceiling and tile.  

Tailor these amounts to the significance of the task; for example:Roofer: $1,000/day (critical to weatherproof the site).Painter or garage door installer: $100–$200/day.Contract Value & Payment Terms:Agreed payment amount (lump sum or itemized costs).Breakdown of payment terms:Deposits.Progress draws.Retainage (if applicable).Scope of Work:Be as detailed as possible.

The loan has a payback period of 5 years in equal installments.