… and phones with a 1G per month data cap, and no connectivity half the day.

1G? That's so generous. Try surviving on 20MB a month.

It's possible, but you really notice whenever things fail to be cached. (I'm looking at you google maps!)

You can save an offline version of a Google Map in the smartphone app: https://support.google.com/gmm/answer/3273567?hl=en

Yes, but it will get deleted if your phone runs out of space (at least, that's what I'm assuming happened to the map, because I did download a local cache before leaving the hotel).