Like the other said, a wheelchair or ecv would help you a lot more than a GAC (Guest Assistance Card). The GAC would only be for when you are in lines, which is actually a very small part of your park time. A wheelchair or eccv would allow you to cover ground without using up your enerrgy to do it (when you are recuperating from surgery, you want to spend as much time as possible doing fun things rather than just getting from place to place).
About the liquid stitches, I would suggest asking your doctor if you still have questions, but since he said you can go in the pool as long as you just wade, I would do that. Regarding the liquid stitches in water; (and don't be shocked at this) liquid stitches are basically a compound similar to Krazy Glue. if you have ever glued your fingers together, you probably found out by experience that water doesn't dissolve it. After seeing a lot of people come to the Emergency room because they had glued fingers to various other body parts, doctors started to think that stuff might have some actual medical uses, and the rest is medical history!
So, hope you have a good time