Surgery won't fix your swallowing difficulties or gastric emptying, but it's essential that the surgeon has asked for the tests because it makes a critical difference in the type of surgery to perform.
I have low swallowing ability, so when I had to have my fundoplication the surgeon did a partial wrap - a Toupet Fundoplication - so that I can swallow past the wrap.
For the emptying it's possible to just make a few changes in your diet. I won't promote the available medications (USA) because metoclopramide gave me muscle twitches that took months to resolve, and there are no others that work. For the low amplitude of swallowing you have to beware of trying to swallow anything too large, like vitamins, calcium, other tablets. Coated capsules seem to go down better. Sometimes I have to concentrate hard to not take a quck breath when a pill gets stuck. Gagging is one thing, but inhaling it is worse. I often take tablets with milk to coat them.
Most people get a common hiatal hernia sometime as they age. It's usually of no consequence. It makes only a little difference in the surgery because the opening has to be stitched closed. The type of hernia where the stomach stays stuck in the chest IS dangerous because the stomach can twist and strangulate. But that's rare and they would probably have told you about it.