need(n't) and others

I DON.'.T NEED that cap.
We need to talk, needn't we ? NO
We need to talk, don't we ? YES
We needed TO do that, didn't we ?
-- And others sentences which I am not VERY sure about? :
Have you talked with him YES. Have you talked him NO or Have you talked to him?YES Either 1 or 3 works. 1 has more of a connotation of carrying on a conversation. 3 has kind of the connotation of more formal, maybe mostly one-way interaction. You talk to your boss. She talks to you. Your kid has been screwing up, so you talk to him.
I need to see a doctor or I need to see with a doctor NEVER with "with"
--
There is a situation WHERE I have to pick one picture of the three. (YOU COULOD PROBABLY LEAVE OUT 'THE'')
Can I say IT like that ?
I would pick the second one (third one) because ....

That's all. I wait for your answers

There is no "needn't" ?
How can I use that word ?
Why I can't say : " I needn't that cap"
"We need to talk, needn't we ? "
I will be thankful if you explain that for me.

"needn't" is a word that is used extremely rarely. If you're learning it an ESL class, be prepared to never use it. "Don't" in the se ntences I used it in is FAR more common. And it's "why can't I say...."