Your villagers will eat when they need to. While you can feed them if you wish, it's not necessary. You need to train your villagers to gather food and increase their research so that they can become more and more self-sufficient. Setting their preferred skill on the Details screen will help them stay more focused on their work. There are some strategy tips for getting started successfully in
this post that might help you.
How quickly your villagers age depends upon the game speed setting. On normal speed, they will age 1 year every two hours, and a baby is weaned at age 2.