Hi British Beef,Welcome to the Healing Well 
Wrapped Club! Like Alcie, I think your symptoms are quite normal at your point in the recovery process. And like Alcie, I'm not a doctor, but did have this surgery three and a half years ago and shared many of the symptoms and concerns you have. In fact, here is the link to my early recovery journal that I posted here on the forum:
https://www.healingwell.com/community/default.aspx?f=45&m=2183443
I'll try to speak to your questions and concerns:
1. As of last yesterday afternoon and today I have developed a horrible sour taste in my mouth (mainly all over my tounge - especially at the back). With my constant anxious state I am immediately thinking it's 'Acid' and the wrap has failed. However I am not getting other reflux symptoms (like burning or pain I used to get with reflux).
There is a very good chance that your wrap has swollen due to the trauma of surgery, and food/liquid is being held back at the wrap site. This is a very common problem, and nothing to be concerned about. Actually, your wrap becomes increasingly more swollen over the first two weeks. After the swelling peaks at or about the 14 day mark, you'll begin to experience gradually improvement. This is totally normal.
I actually called my surgeon to ask about reflux symptoms I thought I was having. His response was that at my stage in recovery "anything was possible". There could be food and drink held back by the wrap, or it was possible that the swollen and misshapen wrap is letting a little acid through. Either possibility is nothing to be worried about.
It takes a full 6 months for the majority of healing to occur, and a year for the rest. You're at the first baby steps of recovery, and will certainly have lots of bumps in your road to recovery. It's totally normal and to be expected.
2. For 2 weeks before the op I started coughing up mucus. This is still happening post op and I am concerned that the coughing could damage the wrap. I was told by hospital staff that I had to cough the mucus up otherwise it could turn into a chest infection. They also said that coughing wouldn't damage the wrap. I have read since that coughing is bad though??! I am coughing carefully and not having coughing fits or anything like that but it still concerns me.
If you read my early recovery journal you'll see that I coughed hard and nonstop before, during, and after my surgery. Like you, I worried that my wrap would be damaged. I had an additional risk factor in that I had been on high doses of steroids and my internal tissue was extremely fragile. Because of that, I was even more worried. I had tons of mucous to cough out, and it did hurt to cough.
I can tell you, though, that I had no damage done to my wrap, and it has remained intact. Alcie is correct...hold a pillow to your stomach when you cough. Also if you irritate an incision with your coughing (my left rib area incision was extremely painful) I recommend ice. I lived with ice on that spot until the healing process took over and the pain subsided.
I coughed a lot for a full two and a half months until the healing process cleared my my poor lungs. It almost seemed as if it happened overnight, but of course it was a long healing process.
3. I am having a hard time drinking much fluid. I can only sip every 10 seconds or so or I get the feeling I need to burp and then it hurts in my chest a lot as my body goes through the motion of burping but then it feels like the wind can't get past the wrap which I guess causes the pain - is that normal?
If you're anything like me, swallowing is painful at your stage of the game. I didn't even want to swallow my saliva at that point. Be sure that you're not using a straw, as it introduces more air into your stomach and creates more bloating. If you read the description of my swallowing in my recovery journal, you'll get an idea of the painful swallowing I experienced.
Avoid iced drinks, as it can cause spasms in your esophagus. It's normal to have bloating post op and not be able to get any burps through the swollen wrap. Don't try to burp. The best burps at your stage of the game is when your stomach burps itself. You could try chewable Gas-X tablets. They can be helpful.
4. Eating is a little easier. I am only eating soup, ice cream, jelly (jello) etc. I eat slowly and after a while I get the same sort of pain I get when drinking. It feels like I need to do a big burp and hurts for a while. Does that mean I am full when this happens? I don't get the normal feeling of being full so am trying to work this all out.
Ice cream is very cold and can create some of the esophageal pain I mentioned. If you don't get full, be sure to limit your intake to 1/4 to 1/3 of a cup at a time so you don't overfill your stomach and create pain and irritation. Eat many meals throughout the day. Try warm tea or soup rather than ice cream. I think you'll find it easier to take.
Glad you've joined us! Stick around for lots of support from others who've had the same recovery experience.
Very best wishes,
Denise