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Situation 1 is very difficult. You eliminated my first choice which would be to back up and run probably getting off a few rounds. However since that is not an option plus my family is also at risk my only options are surrender or try to get away on foot. I would most likely run on foot and hope we can find shelter or a place to hide as well as be missed by their inevidable initial gun shots. I would probably not return fire since my muzzle flash would give away my location, cause the enemy forces to know I am armed as well as be more hostile to me and my family if caught, and also remember most mlitary soldiers (even the mexican military) wear some form of body armor that will most likely stop a pistol round. My family's lives come before mine but I can do them more good alive than dead or captured.
legally as far as I know a foreign military or police is not allowed to possess a firearm while performing an enforcement scenario. I may be wrong on this but its what I was told by a DEA agent a few years ago so section 9 would most likely apply to both scenarios.

Situation 2 is a bit easier I would order my family into the panic room and try to hold off the troops the best I could till either I could get them out of the house and into a safer location or try to divert the troops towards me and lead them away from my family.

The movie Red Dawn raised some good questions like this to me and could easily happen if Mexico allied themselves with an antiamerican country like Cuba, China, or N. Korea; unlikely but possible. There is a difference from being prepared with some form of plan in the back of your head and being an apocoliptic nut job.