They tend to look for the things they would fix and if they're not a roofing contractor, it might've been overlooked (although this really is a head scratcher to me because it's pretty standard.)

I am reaching a point where I am starting to build up some cash, so I am looking into ways I can invest it and increase my cashflow for years to come!

75% is standard. 80% rate and term dont take the bait. 

But I note that foreclosures are increasing. 

Is there a standard, good, or bad system out there?

It has been booming for the past couple of years with strong job growth and population increase.

And if so, what is the cost and prospect for collecting something, certainly not all, but something.My thinking is that if it shows up on their credit, it may hamper employment, car purchases, rental applications, education funding, etc and at some point they would need to pay me to go forward with some major life steps over the next 10 years.Your time and money would be better spent updating your rent requirements to get better tenants, increasing deposits if allowed and proactively evicting tenants who are behind so you don't get back in a position where someone owes you a substantial amount of back rent. 

Any investors in the Houston area with experience in building an addition for a home to increase square footage and add value?

These are, or should be standards in design and build, that translate to any and all economic markets:1 - Treat the design as the first few times (changes) you will build, and pay for, the house.2 - Treat the design as a system, made up of a series of interacting systems.3 - Understand that design is a series of decisions, with each decision impacting more than just the immediate decision you are making. 

The shorter the prepayment term has an impact on increasing the rate.4.