You'll need a vapor barrier and insulation on the garage floor and stem walls.   

No due diligence with non-refundable earnest money.With her being from California, I told her "we don't do that in Texas."

Hypothetically, if you felt sorry for her b/c of the 11mo old baby and wanted to give her a break b/c of that situation, that could be interpreted as discrimination based on familial status - even though it may *feel* like you're trying to do the right thing.Step 1: determine your criteriaStep 2: screen applicantsCould the Mom be a co-signer on the lease? 

Based on your follow up post about her being a chemist and his VA check being 3x monthly rent, my concerns were unfounded.I was partly concerned about this possibly being a common scam.

let her be move on geesh. 

There is a risk of that bank not wanting to refinance after 5 years, either because they need to reduce their loan amounts, the market vaporized (with your equity), or current interest rates make it un-affordable for you. 

I actually believe, but don't quote me, that cement board is code in my area for the whole shower.Since it's the kitchen, we're really looking at vapor contact via humidity in the air.

For reference, we're talking a 24.5' x 24.5' slab 4" thick on grade w/ #3 at 18" on-center rebar with 15"W x 12"D footers, 2" sand over 10mil vapor barrier over 2" sand.If anyone knows someone who is reasonable in cost/licensed (and bonus if they can do the rough plumbing design underneath the foundation), please let me know! 

(I also have it on the inside of the framing for a vapor barrier.)On the flooring, some people use the plastic padding, but I've been in too many musty basements. 

Put a 6 mil vapor barrier over top, seal the edges, add a silencer pad,  and put a nice bamboo floor over top.