For this instance, look into Nevada and Wyoming to set up your LLC's as they have the best laws for Single Member LLC's.

I want to be good to these folks, but I don't want to risk losing everything I've worked for because they used a hack to get at the natural gas, for instance.

For instance, I do not know if one or both of the tenants have moved out.

For instance one reason a property can have a higher price is it has work done to it. 

Displacement of tenants - Let's say for instance that your tenant who's boyfriend has appeared to move in, does actually live there and you are inadvertently accepting funds from the boyfriend.

If you include the rental income it would in this instance, but what if I did not have any other proof of income?

not necessary in most instances..

For instance, a landlord I know had a unit at first was going to be offered as is for $1800 but after a $45K renovation upped it to $2500.So, where I'm going with this is: is it fair to also increase the rent if a tenant requests the unit/building to be deleaded?

Again... some of the numbers required guestimation- I am using the average of my rental income comps for instance.

However, there is not much you can do, for instance, recently, when a teenage son of one of your long-term tenants decides to punch holes in walls and kick in the front door.