My sister is selling her house to me; however, we want to do a mortgage transfer since she currently has a 2.5% interest rate, but the bank will only pay what is owed on the current mortgage.

You should research STC rating options.

Unlike traditional real estate notes is something that is easy to do from afar since you do not get access to the interior anyways so there is nothing you can physically inspect.You are correct that you will get $500-$600 a month in payments but also recognize its taxed at ordinary rates... 

And only private money should be taking a percentage of the profit at a lower rate.

This avoids the seasoning period and still allows conventional financing for the best rates. 

MLS, negotiated 12k seller credit for rate buydown.

To start, I'd do a Discounted cash flow analysis and cap it like a regular income producing rental....do you know the rent the tenants were paying in the two sales you showed?

Most markets in Florida are quite lucrative and have higher and consistent occupancy rates year-round because of the weather.

Assuming the rate of $5 per 1,000 gallons that would result in about $35 per year saved in water per shower head.

We got his friend discount of a final bill of $131,000 and he wants to get paid immediately.