2nd home sale how and when to pay tax

We recently sold a vacation home (occasional rental property) we owned for just over two years. I think I have calculated the tax due - price received less purchase price.

Question in 3 parts:

- We sold on Oct 31, when do I need to pay the estimated tax by?

- How do I pay it (would prefer to wire transfer than mail a check if possible)?

- Are there any other deductions we should take on top of the original purchase price, maybe improvements?