Sorry to recycle a post. This question came up before, and this was my answer:
This site is the Know Before You Go page, and seems to have a lot of great info!
http://www.customs.ustreas.gov/xp/c.../know_brochure/
A link from the above page is the What You Must Declare page:
http://www.customs.ustreas.gov/xp/c...ure/declare.xml
A quote on this page answers your last question about the camera:
"Register Items Before You Leave the United States
If your laptop computer was made in Japan - for instance - you might have to pay duty on it each time you bring it back into the United States, unless you could prove that you owned it before you left on your trip. Documents that fully describe the item - for example, sales receipts, insurance policies, or jeweler's appraisals - are acceptable forms of proof. To make things easier, you can register certain items with Customs before you depart - including watches, cameras, laptop computers, firearms, and tape recorders - as long as they have serial numbers or other unique, permanent markings. Take the items to the nearest Customs Office and request a Certificate of Registration (Customs Form 4457). It shows Customs that you had the items with you before leaving the U.S. and all items listed on it will be allowed duty-free entry. Customs inspectors must see the item you are registering in order to certify the certificate of registration. You can register items with Customs at the international airport from which you're departing. Keep the certificate for future trips."
An example of Form 4457 is at:
http://www.cbp.gov/xp/cgov/travel/l...egistration.xml
Another link which is between the Know Before You Go and the What You Must Declare
http://www.cbp.gov/xp/cgov/travel/l...ginUS/vacation/
You can call the local US Customs office yourself for specific question.
Hope this helps a little!