there's rumors that this'll last until summer maybe so might want to be prepared

Most places will deliver to your house, some for quite cheap or free if it costs over a certain amount.

They have Mexican restaurants but some are quite expensive. And it depends if you're looking for more TexMex or like...Mexican food.

I haven't had too much trouble using my card on my business trips, but maybe it's because I stay in Tokyo. But definitely carry some cash with you because some places don't accept cards.

If you want traditional Japanese things, Nakamise-dori in Asakusa is a great place. You can get everything from keychains to snacks to swords.

Like the others said above. But sometimes, even though the smoking and nonsmoking is separated, you still end up smelling the smoke. So sometimes you gotta step in and check first.