Instead use two or three data sources and average them together.

If possible I would want the amortization over 25-30 years.I know cash out refi is quite expensive with the origination fee and everything, early pay off could cost too or drive the rate up.

That's odd, because I could have pulled an extra $35K out over and above my out of pocket expenses. 

Goal is to profit an average of $10K per deal. 

What's the best way to track your property income/expenses for tax purposes?

It's a bit of a luxury, but once it is set up properly, it is very easy to track income and expenses.

If you- own a short term rental in your name- have a mortgage on that property - self manage Do you still create a LLC to manage your rental business or do you manage it under your name and then file income and expenses as part of your tax filing?

3- Can I use this strategy and deduct all business expenses if I finance the property with a secondary home loan, or should I only get an investment loan?

The short-term rental is a bit more work, but it covers a lot of their expenses. 

The average buyer has no idea how to conduct a transaction, especially if they move from market to market / state to state.In my market, buyers aren't used to signing anything with a buyer's agent.