The only thing you will need is a local handyman and plumber that you can call on when needed.

Your handyman has a reputation to uphold so his references hopefully hold water.

If Austin doesn't go full left-wing-permissive-seattle-style and ensures those services have conditions and boundaries, so that they don't get the "Freeattle" reputation then the shelter won't draw an outsized proportion of people from all over who just want handouts,  instead it will be more likely to draw people from Austin actually looking to turn things around.   

He told me he'd happily do it, but it was going to be a list of items I already knew by looking and a lot of "call a roofer", "call a plumber", etc.

When cleaning the bathtub, prepping a new rental, the paint started to heavily chip off the metal tub (think last owner/tenant did a hack paint job).Called a couple of plumbers and was quoted 4K-10K to replace.

Toilets all flush down the same size pipe so my plumber says it's not worth the extra money.

We recieve them from our regular lawn care, plumber and electrician.

Where do I begin?

A hydrostatic plumbing test is recommended to be performed by a licensed plumber post Foundation work.

They have a great reputation down here and are investors themselves.