Can a pancreatic pseudo cyst pressing against the stomach cause excessive burping
It's not very likely. However, if it was caused by pancreatitis, then that would be the reason for you burping a lot. You should see a doctor. More information is provided at http://www.healthcommunities.com/pancreatitis/symptoms.shtml and http://www.webmd.com/heartburn-gerd/tc/gas-bloating-and-burping-topic-overview.
Probably not. Excessive burping is a result of indigestion or too much acid produced in the stomach.
I'm no doctor, but I'm betting that ANYTHING pressing on your stomach from the inside is going to have uncomfortable side-effects!