The landlord will say the the rents are current and the tenant will confirm the lease , terms and duration, and security deposit.

I noticed a house on my block hasn’t had anyone in it the duration of my time in my home.

Here's the deal though, I'm pretty sure they have to have exclusive use for the duration of the time period set up by your state for adverse possession.

The HELOC usually have lower costs, but for longer term loans the cost when spread across the loan period(I have never had a loan over 15 years) is small. if you plan to have the loan for a long duration, you may want to consider a refi over a HELOC due to the fixed rate.  

How much will the fees/points + interest be during the duration you'll have the loan.

Then add in the winter storm in Feb where there was record cold temps for a record setting duration and add in power outages.  8 units with frozen pipe related issues some with expensive emergency repairs.  

;Keep properties for long duration.; ..Two member (Husband + Wife) partnership.

Shorter duration on the weekends.

I am wondering about the content of my lease: The base rent for the duration of this Lease is $19,800.

The answer is very different for a multi family due to state wide rent control.You have the notice duration correct when tenant is on a month to month lease and has lived in the unit over a year.