I had surgery in Novemeber of 08. I started by telling just a few friends and co-workers, including my boss, who I had a close relationship with. I told my coworkers (there were a total of 8 of us who worked together) just before I had the surgery, mainly because I knew my eating habits would be so obviously different when I came back to work, and we all ate lunch together as a group.
As far as post op complications: if you are having your surgery in Mexico, I assume your insurance did not cover bariatric surgery, so most will not cover any complications that can be directly related to your surgery. Be sure that you have someone lined up at home to follow you post op, whether it is a local bariatric surgeon (you will ususally have to pay a "transfer fee"), a general surgeon, or your primary care doctor. There are lab results that need to be monitored about every 6 months for the first 2 years, then yearly after that, especially if you are having the sleeve or bypass. Be sure you are compliant with your multivitamins, B12, and calcium post op. Best of luck!