Remember that in America it's not rude to talk about problems or difficulties. It's actually best to solve problems right away. Then, they won't become too large. Even if speaking English is difficult in the beginning, your host family will appreciate it if you are open and friendly with them. This will create a comfortable environment for everybody.
Most families have rules of the house.
Even if they don't talk about these rules, it's wise to ask about your host family's expectations. A very common rule is to not come past a certain time. This is called a curfew. It's important to ask your family what time you should be home. If you come home too late, you may cause you hosts to worry or disturb their sleep.