Welcome to Healing Well! I'm glad you've found helpful information here. As Kitt said, we'll be very happy to answer any questions you have.
There is one other test that involves a tube being placed through your nose. It's called a manometry test, and it measure your swallowing to ensure that the correct type of Nissen is done. If your swallowing reflex is strong, you'll have a full wrap, less strong, a partial wrap. It's an important test and if your surgeon doesn't order it, I'd question your surgeon's competency.
Here's a video showing someone getting both of these procedures, and I think it might ease your anxiety (unless you think watching it will create more!). I think the manometry swallowing tasks are a little more challenging than the woman subject indicates, but I've had it done twice, and really, it's not that bad. You have to get 10 good swallows and the test is done. The trick is to not swallow in between. Bill, a moderator here, has had this test many times, and he suggests sticking your tongue out and holding it between your teeth between swallows. (If you swallow between required swallows, it takes longer.)
Anyway, here's the video, FYI.
Good luck with your apointment! Let us know how things go.
We'll be here to answer questions and support you through the whole process!