Most of these houses lack insulation, have old single pane windows, have galvanized/copper/cast iron/PVC plumbing all in the same house, post-n-knob electric or cloth wiring or both, and lots of bad remodeling done over the years.

I would suggest finding direction first man you seem all over the place and are always chasing the shiny penny.

I had a hot water line corroded at a T fitting, and had to replace the fitting which was behind a wall and about 15 feet of copper piping.

It's the higher-risk sector of investors, and while there are many who do it, it just doesn't gel with the BiggerPocket's culture.I would compare it to those who throw their money into mutual funds - expecting a safe (albeit smaller) ROI vs the crypto-currency or penny-stock subgroups. 

Im currently under contract for a my second rental property i had the inspection done Saturday and my inspector found aluminum and copper wiring and he said the house would need to be rewired.

Also, I've been lucky that the two leaks I've been hit with were relatively slow leaks - do most roof leaks start slow or could be very much the contrary and I may land up being penny wise, pound foolishIf anybody wants to recommend a roofer that'll be cheaper than the quote I've gotten and often works with landlords, I'm all ears - NYC areaThx

I believe that great legal counsel is worth every penny and absolutely necessary to execute a syndicated deal but you do want to consider how you spend your time with counsel. 

I had the same problem this spring. 2 coats of Kilz and it still had a faint odor.

The property could have used carpeting (which has since been completed) and a fresh coat of paint on the walls would have helped, but at the time, I just needed some additional cash from the property as it was free and clear at the time (now has a 37k lien on it). 

Or a cold water pipe - assuming it's copper, not pex.