There has been no tax benefits per se.  

Taxes are also always going to be a consideration, and this is an assessment year, so you should account for them going up more than usual in your projections.  

Ignore the loan when trying to factor in the possible tax implications as paying off a principal balance doesn't do anything tax-wise.

There was a property at the auction that sold at market, however it had a federal tax lien of over 100k attached to it.

I pulled them from the tax assessor's website, just going one by one through each parcel to locate and identify the vacant lots.

Typically, it just refers to the number of units/leases you have, not the number of tax parcels. 

I have some questions about the material participation rules for the STR tax loophole.

Given that you've owned them for almost 5 years, there is also a good opportunity to do a cash out refinance and obtain tax free money that you can use to expand your portfolio even further. 

When evaluating rental properties, aside from school districts and convenience, consider factors like neighborhood amenities (parks, restaurants, shopping), rental demand, job market trends, property condition, potential for appreciation, and rental income compared to expenses (including taxes, insurance, and maintenance).

@Tracy Derickson Click on the Build your Team tab and you can find sponsored vendors for tax and financial advice here on BP.And as @V.G Jason stated give us a fact set and you will get free advice on your case on the forum.