Grammar and Tenses

Hi! Are all these conversations written correctly? Also is the sentence correct? Thanks, Fulvio

Conversation 1

A: If you won a million dollars, would you buy an island?

B: Yes, I would.

Conversation 2

A: If you win a million dollars, will you buy an island?

B: Yes, I will.

Conversation 3

A: What would you do you if you won a million dollars?

B: I would buy an island.

Sentence

Tom said he would buy an island if he won a million dollars.