So after COVID when government was giving away 6 months of Principal and Interest as rebate, I started looking for a property but couldn't find fast enough.

The comps are between $118-$141/sqft, but it was purchased at $148/sqft.The loan is assumable at 2.75% rate ($139,383 principal remaining) but will cost $900 application fee and  between 1-5% of purchase price (assuming 2.5%).

When you run numbers through a model you realize that even with potentially higher rates, you'll refi a lower principal against higher rents and higher property value, so it is mostly an emotional conern rather than a financial issue.

I heard about it on Keith Weinhold's Get Rich Eduction podcast, ep. 240.https://www.ridgelendinggroup.com/aio-loan/https://www.getricheducation.com/episode/240-new-1...Line Of Credit for 30 years80% LTV on home, 70-75% LTV on investment propertyNo principal payments due for ten yearsI believe Ridge has closed more investment property loans than any other company in the country.

Some of the principal protections of real estate include:Limited SupplyLeverageRental IncomeTangible ImprovementsDiversificationProperty Appreciation Tangible Asset Hedge against currency devaluationDemand FactorsDuring inflationary periods, real estate investments have historically shown an average annual appreciation of 5-6%.

Do I have to pay taxes on the $25,000 of the progress I have made on the principal?

The principal and interest payment will remain the same, but the loan payoff date will be escalated as you make extra payments towards the principal.The details of your monthly payments should be available on your monthly mortgage statement as it lists the principal, interest, taxes/insurance escrow, and PMI paid that month.

The loans evaluate the property's ability to pay the principal, interest, taxes, insurance, etc. from the rental income without considering the investor's separate W2 wages. 

I would talk to the original lender before you make any principal payments.

If you have good cash flow on your properties, there is an argument to kill some of the debt with high interest of high K factor (large principal, small interest payments).