My mother-in-law is saying that my wife needs to sign off on the loan.

Never lend in second position unless you have the wherewithal to pay off the first.

Off market deals usually have nonrefundable deposits and a clunkier process that isn't as suited for out of state people until they have good contacts in the area to evaluate the property (mostly contractors that feel comfortable evaluating projects for you).

Our goal is to be able to use either some type of software or spreadsheets to continue to build off of and help dial in our costs as we begin to hire more contractors for our team.

Sounds like she has a loan on the property still so the only way to get the deed into your name is to have the loan paid off like normal. unless she has an assumable FHA loan. 

If you have large debt with a high interest rate, I would consider paying that off before getting started investing in real estate. 

Obviously the answer is yes when it comes down to the cash flow, but I am particularly wondering if HCOL/high property tax areas are places you would cross off the list entirely.

Purchase price: $230,000 Cash invested: $283,550 Sale price: $283,500 Purchased off market. $25,000 Rehab. $20,000 profit after realtor commission.

I've been interested in real estate investing on/off over the last two years.  

Then wherever the water is getting discharged off of the roof, that what water is getting at least 4-5 foot away from the structure before it is left to drain with gravity away from the property.