Towards the middle the gap between the tub and the Tile was getting significantly bigger then a quarter inch.

The taller of the twois 12 feet and 6 inches of clearance.

My tenants informed me on Wednesday, (2 days ago) by text that they think there is a leak in the roof above the master bathroom and sent a picture of what looks like a slight bubble in the sheetrock paint about 2.5 inches in diameter.

There was trash all over , broken furniture , wood and piles of junk ,god know how many piles of dog poop, and an inch thick of dog hair!  

If you happen to have a 1.5 - 3 inch drain that somehow has become corroded despite the fact that water is being run down it constantly (meaning that's actually rare) then it's the landlords problem.

Some contracts have enhanced death benefits with fancy features for an additional cost.  

When I got there...the foundation had dropped 6 inches on one side of the house, a pool had been improperly filled in, no ductwork for HVAC....it was so bad.

Go down 6-18 inches and you hit rock. 

Depending on how bad is the foundation state (how many inches you have to correct), is very possible the sewer line will disconnect/break in the horizontal portions.

Does anyone have other suggestions for those valuable skills that I could do part-time while building my portfolio and enhancing my REI skills in general?