The I-94 form is a declaration of what goods you are carrying into the country from foods to cash. Fill it out completely and correctly, then when you pass through immigration at the U.S. port of entry the inspector will make a notation of the date of entry and mark your visa status, then staple the I-94 onto your passport.
According to American laws, there are no customs taxes at entry for personal goods, if they have been used as private title for at least one year. Cars are in this category. Nevertheless, you must have a copy of your registration document and check that it corresponds to the norms of the state.
Animals, in spite of a rigorous medical visit before departure, will be sent to Coventry by the American authorities. Make sure to have the animal up-to-date on all medical treatment including shots and have had it examined by a veterinarian within the last 30 days.
For a complete list of custom requirements and to search for particular information, go to United States Customs.