Aloha,While associated fans may be multi-speed, the actual "cooling" mechanism- compressor, evaporator, condenser, coolant lines and controls, are not.

Day of the install after all the material is off the roof you’re asked for more money due to lack of material, i.e. compromised wood that was not inspected when it should have been.Just like a mechanic, you probably wouldn’t trust him if he told you you needed a new transmission but never popped the hood. 

Regarding placing liens on homes, I'm pretty sure the lien may have to be related to the home (i.e. promissory note to home, mechanics liens, etc).

What's behind that door, in the garage, how's the mechanicals look, is their water stains anywhere on the ceiling, etc. 

What will be your finance mechanism?  

. $30K should be more than enough for fresh paint and flooring and some other odds and ends, but if you need dry wall, cabinets, countertops, mechanicals etc it could get much pricier. 

4- of course we'd want to verify it's permitted use per zoning5- Capex will need to be budgeted for a reserve account for tax purposes6- need to get the stage 1 and 2. 7- by subcontractor issues do you mean a mechanics lean on the property?

I’m also in DFW and interested in doing a hybrid of owner/builder after the mechanical phase.

2) Are Vendor Mechanic's Liens extinguished at tax sale? 

Closeups of all mechanicals (hot water heater, furnace, etc.)