Selling Investment Rental Property:Tax avoidance options and 1031

[Anurag D.]

Hi,
We are contemplating selling one of our investment rental properties in a profitable market, and intend to encash all money.

We had below queries:
Sell Price = Initial Principal Downpayment + Loan + Closing Cost + Taxes - Depreciation + Capital Gains

1. Are Taxes based ONLY on Capital Gains or (Principal Downpayment + Capital Gains)?

2. 1031 Like-Kind Exchange:
- Is it possible if we cash-out Initial Principal Money AND use Only Capital-Gains, as part of 1031 like-kind exchange, to purchase new investment property.

3. Can Capital Gains be used to pay mortgage debt for my another CURRENT investment-property as part of 1031 like-kind exchange?
-And, cash-out Initial Principal money.

Thank you in advance.