Based on a prior gift purchase there I was given two passes which show an expiration date of 2/8/2018. So I need to use them soon. How do I use them? Do I need reservations or just show up and hope for a seat?

You can use gift cards online after selecting seats. I do it all the time

Gift cards most be used in person, but you can purchase tickets in advance at the box office, which i recommend.

You can do both. You can go on their website and choose what movie, time and seats for when ever you want. It also can be months in advance too. You Don't have to be make it the same day.

If you have a gift card you can purchase tickets at the box office and hope for seating (unless its a new hit release you should be ok) or go to their website directly and book the tickets