Deductions & credits

When I am deducting  investment interest on the underlying mortgage via Schedule A, what items are allowed:

  1. Mortgage interest 
  2. late charge and fees incurred
  3. Can I deduct principle paydown payment? I am not sure that.
  4. Escrow account is with Underlying mortgage. I don't think I can deduct escrow payment made by endbuyer like Mortgage Insurance premiums, property taxes and insurance. Correct!

As I was reading IRS pub 936 and IRC Sec 453, I came across IRS Publication 537 (Installment Sales). I am not sure my real estate wrap around transaction follows Pub 537. I purchase wrap-around mortgage note from another company. My LLC did not sell the property with an installment note. Let me know expert thoughts thanks