That's too bad. I don't like it when that happens (although it most often happens to me when I get busy and forget all about them until it's too late).

The farm is programmed to produce crops roughly every 2 game years (the number of hours will depend upon game speed), and you should be able to support about a dozen villagers with just the farm and the berry bush. Depending upon how often you're checking the game, you may not see crops on the farm, though, since the farmers will harvest them while the game is off. You can check the game's stats screen to see how much food has been harvested since the last time you checked. That should help you determine if there's actually a problem.

The skill level of the farmers doesn't have any effect on the farm's crops (master farmers have another benefit that comes into play later in the game). If you're monitoring the game closely enough, you can move all of the farmers to the research table while the farm is empty to help get the tech points necessary for the final level of farming technology. Then just put them back on the farm when there are crops to harvest.

The villagers' curiosity is there to alert you to various areas of the island that are important. They don't produce skill or tech points, so you're safe in just dragging them back to work (like most of us do)!