I know that it is screaming SOMEthing odd is going on, but I am too inexperienced to tell what's going on.

You do not want to leave a gap as wide or wider than the thickness of your baseboard .... else you end-up using quarter-round or cove to cover the gap (screams short-cut or quick/cheap).As for your closet doors:  lift the tracks; lay your finish floor; put the tracks back down.Your vinyl plank is going to expand very little.

She dragged me in, kicking & screaming. 

This screams scam to me, but of course enticing.

So Jack starts bad-mouthing previous plumber & hyping his own work.Jack says he’s going to snake the line & I went outside to do something else.When I saw Jack come outside & start putting stuff in his truck, I asked him how it was going, & he started loudly screaming at me that he got chemical in his eyes & I’d lied to him about chemicals in the drain & I was an bad person & he should call the police, etc.

I'd also negotiate a screaming deal with the seller based on the "foundation issues".

That screams "start up" and everyone will instantly be skeptical lol. 

However, unless the property is really a screaming deal, I tend to avoid the headache of this approach.

They can be dramatically undervalued because residential lenders run away screaming.

In my area of investment there are many of-turn-of-the-century properties that scream for renovations but those areas are full of rundown, abandon drugs infested properties.