RE: taking guns to mexico
Call me xenophobic, but I wouldn't travel into Mexico to hunt if you PAID me money. As my screen name denotes, I am all about keeping the hunting $$$ in the U.S. I do support free trade and I own some Nikon optics, for me, there's just too many places and species to hunt in the U.S. before looing elsewhere. Just my $0.02.
You're obviously smart enough to ask some good questions before the trip; I would advise going a step further and making at least one phone call to an attorney--just in case a nightmare unfolds. Good luck.