I want to rent a movie, but I want to know if I can pause it and watch another time or if I have to watch the entire movie at one sitting?
What channel are you referring to that offers movie rentals? There's a number of them. Generally, most allow you to pay for the rental and begin playback within perhaps 30 days. Once you've started playback, you usually have 3-5 days to complete watching it. But without knowing who's offering the rental, I'm merely making guesstimates based on what I've seen from some providers.
Prime Video - I want to watch Night Crossing - rent is from $3.79.
Amazon can answer that question. I think they are similar to what I mentioned above.
Amazon says: “For rental videos, you'll typically have 48 hours to finish watching the video once you have commenced streaming or downloading, provided that in any event you must finish watching the video prior to expiration of the applicable expiration window, which is typically 30 days from your payment of the rental fee. The length of this window can be found on the detail page or on a link from the detail page, such as the "Learn more about renting and buying" link on website detail pages.”