Help me with these, please.

Experts,
As conversational phrases, which one(s) of the following would you say more acceptable? Or more commonly used, or less strange?

When going to a party:
Jeans and T-shirt would be fine.
Jeans and a T-shirt would be fine.
(possibly 1st one?)

When inviting someone to your place or to a party:
We got everything we need, so don't bring anything.
We've got everything we need, so don't bring anything.
(possibly 2nd one?)
Bring you own beverage.
Bring your own beverages.
(possibly 2nd one?)

Asking about one's schedule:
Are you busy/free May 23rd?
Are you busy/free on May 23rd?
(possibly both?)
Are you busy/free Monday?
Are you busy/free on Monday?
(possibly both?)
Do you have any plans tomorrow night?
Do you have any plans for tomorrow night?
(possibly both?)

When replying to an invitation:
Not on 10th, I'm busy that day.
Not on the 10th, I'm busy that day.
(possibly both?)
Unless something (else) comes up, I can make it.
Not unless something (else) comes up, I can make it.
(possibly 1st one?)
Sorry, I pass this time.
Sorry, I'll pass this time.
(possibly 2nd one?)

When asking for a favor:
Would you mind if I ask you to help me with this?
Would you mind if I asked you to help me with this?
(grammatically 2nd one, but colloquially both?)

Thank you very much.