So, yes, bringing food is part of it. A lot of people tend to bring sweets and, while there is nothing wrong with that, if you are able to, anything that is more meal-like or substantial would probably be appreciated...but sweets are fine as well. Most Jewish Americans are not kosher, so if you have not heard that they are, I would assume they are not and the only food things I would stay away from are things that mix dairy and meat (in fact something vegetarian would help you avoid this concern) and nothing with pork/pig..not all Jews follow these rules but a significant amount do.
The actual Shiva is just sitting around talking for the most part...visitors come and go as they wish...sometimes the family will have mirrors covered because that is a related custom, but in general it will be similar to visiting someone with a lot of others there shortly after someone dies.
lucky single mom to 20 yr old dd and 17 yr old ds through 2 very different adoption routes