Do you need to be a Westchester county resident to go this park and use the pool?

Yes but Mon thru Thursday is free no park pass

You have to be a resident of Westchester if you don't have a park pass and it's $15/person or child. If you have a park pass it's a discounted rate and you're allowed to bring others in for a discounted rate. They only allow a certain amount of people per park pass/resident ID.

I don't think so