1) It's generally a good idea to keep the food supply above 350, if possible, so that your villagers won't be worried about food.
2) Once your villagers have learned how to farm, you should be able to safely increase your population to around 10-15, depending upon your difficulty setting.
3) The game is never truly paused unless you set the speed to "paused" on the preferences menu. If you turn off your Palm when the game is running (unless it's paused), the game will appear to have been running the entire time it was off when you turn the Palm back on. The downside to doing that is that the game is saved only when you exit. If you regularly just turn your Palm off with the game running and something "bad" happens (like a soft reset or crash of some sort), you will lose the things that your villagers have achieved, since the game will revert to the last time it was saved. If you've never saved the game, you'll have to start a new one.
As with all computers and software, the safest thing is to save periodically - anytime you've accomplished things that you don't want to lose. I've never had a computer yet that didn't do bad things sometimes, and Palms are no exception!
