This has been a side thing for us, and our accounting has been old school manual spreadsheets, along with rent collection varying from tenant to tenant (Zelle, PayPal, cash app, etc…) neither of us are great at keeping up with accounting which makes tax time a nightmare.

It is simply the IRS tax law.

Make sure that you have enough cash not only for the down payment, but also to cover the costs of closing, origination fees, property taxes, insurance and so on.

For example the last rental property we purchased we owe on it about $86K and if paid off would cashflow an additional $600 per month.Because of our household income I am worried that paying off properties would bring us into tax brackets. 

I don’t need to submit a No Tax Due Report?

BUT if you do you will pay tax on the difference.You've been told or you've researched and think that you will not pay tax on your original basis and that is correct. 

Looking for a CPA/tax consultant.

Every lenders rate stack is different, so unfortunately only your lender can tell you how many points it'll take to buy down the rate.Break even point = (difference in cost) / (difference in payment)If you think you'll refinance or sell the property before the break even point, financially it typically doesn't make sense to buy down in points (however, consider tax benefits if it's your primary as you may be able to write off the up front points -- which is considered pre paid interest).In you scenario (assuming a 30 year loan), the difference in cost is $3150 and the difference in payment is $52.

The general investment profile of recent investors are second home or vacation home buyers, typically from out of State or area, and looking to take advantage of the diminishing benefit of the 'STR Loophole' of accelerated depreciation to offset high W-2 wage taxes. 

How would that affect his tax situation if at all?