Just to start this off with a warning, I am vegetarian and it can be difficult to find foods in restaurants, but living with a family makes it easier. If you do go out to eat, ask for vegetarian options or you can order something without the meat (sin carne). Depending on the family you are with or the area you are staying you can have three or four meals a day. Breakfast, lunch, dinner, and once. If you are going to try to go out to a restaurant, they do tend to close at "odd" times. Typically their lunches aren't until around 2pm and dinner until after 7pm. Then everything closes around 9pm or 10pm so that they can prepare for the late night crowds.
When you eat at the table, it is very common to have both hands on the table. It isn't considered rude, and you can occasionally be questioned as to why you do not have both hands on the table, although sometimes the younger generations do not.
It is very common to have tea or coffee with every meal. The coffee here is usually instant because "real" coffee is really expensive. It doesn't make it bad, just different.
Now, food!!! There are some different things here, at least different to me. And I am loving them all! My favorite one so far is called "manjar". It is like a creamy caramel that you can put on anything. I usually put it on some warm bread, but I have also had it with walnuts. My chilean mom recommends having it with bananas, and obviously apples would go great with it. If you want to try it, you can probably buy some online, but if you feel like trying to make it yourself, I got the recipe from my chilean mom. All you have to do is boil some water, put in a can of unopened condensed milk (completely covered by the water). Then just let it boil for an hour and a half, the top should be rounded out when it's done. You'll love it!! The other new food that I have had and loved is artichokes. It is normal to eat the leaves and the center. But for the leaves, you just pull the "meat" off with your teeth, do not eat the actual leaf, or the white fuzzy part in the center. To cook it you need to boil water and put in the artichoke(s) in for about 30 minutes, or until you can easily pull the leaves off. Dunk the leaves in lemon and oil and enjoy.