The scammer then ask me if I'll pay him a few hundred to go away, but I told them, shouldn't done that before you got the lawyer, but you now have to deal with insurance.My wife had a younger sister killed by an oil company truck of a major oil company running a red light.

Hello Ryan,I would start with @Brian Burke book "Hands off Investor" as well as some other books such as "Investing in Real Estate Private Equity" by Sean Cook. 

With $600k, I'd be more interested in gas and oil mineral rights and/or a syndication.

The fire was not intentional; the tenant simply didn't pay attention while cooking in kitchen.  

If you were burning fuel oil or coal or something like that stainless steel would be required but for natural gas you can use either material.

The closest to that is environmental coverage for Underground Tanks (normally gasoline or oil). 

I can smell what's cooking

I've heard the Zinser shellac based primer does a better job at locking in odors as opposed to Kilz...or make sure it is an oil based Kilz...Here's a link to a BP cat litter flip forum post from a few years back...half way down page 5 he talks about the smell removal process. https://www.biggerpockets.com/forums/88/topics/133059-cat-li...

Balloon" framing (1920's I believe).Radon.Plaster and lathe instead of sheet rock (pre 1950's) or plaster and wire mesh variations (50's) more solid than sheetrock but a real b*tch to repair or demo if you're remodeling.You've got Galvy plumbing but also need to look out for other kinds of outdated plumbing like clay sewer lines (pre-1930's, prone to collapsing, bellies, root intrusion), cast iron (1950's, often rusted and/or cracked by now), and PB (polybutylene, gray-colored water pipes, 1980's, prone to rapid degradation and subsequent bursting, mostly gone by now).Buried Oil Tanks-- Do you have those there?

Perhaps, the heating system is old and inefficient oil heat and you modernize it to a high efficiency unit with a cheaper fuel like natural gas.