Welcome to the Wrap Club! It sounds like you're doing just fine. You're in the the thick of early recovery, and it's the roughest part. Don't worry about the hiccups hurting your wrap. I've heard of many people having hiccups during the past 3 years on the forum, and have never heard of it doing any damage. It's painful, though, I know.
I had saltines early on in recovery. As long as you can chew them to a liquid, you should do just fine. Have you checked the post-Nissen eating guidelines in the Resources section? GERD - Heartburn Resources
Your stomach feels full after very little food because it is swollen, and your brain interprets that swelling as fullness. As the swelling subsides you will gradually be able to eat more.
The nausea is a result of the trauma your stomach has gone through. Don't push the eating. I know it's disconcerting not being able to eat much, but that will gradually improve. It's normal to lose a significant amount of weight during this recovery. I think it averages 15-20 pounds. Once you're healed more you'll start gaining the weight back.
Are you taking any acid reducing drugs like Zantac or a PPI? Some people take them during the healing stage to make them more comfortable. If your stomach is giving you trouble, you might want to try taking them for a while. It might help with the nausea.
I'd check with your PCP regarding the numbness in your hands. If I had to guess I'd guess they were arthritis-related from being moved around after the surgery while you were out. It's hard on the body when it's moved as dead weight. (I had an elbow problem which caused tingling in my hands...just a thought)
That said, it's not something to make assumptions about, so be sure to talk to your PCP about it.
Words of wisdom by Eckhart Tolle:
"Whatever you fight, you strengthen, and what you resist, persists.”
“Worry pretends to be necessary but serves no useful purpose”
“Accept - then act. Whatever the present moment contains, accept it as if you had chosen it. Always work with it, not against it.”