Small Packets comes with $100 insurance included, you CANNOT add additional insurance.
Small Packets require the WHITE customs form, it's a two part form, you get a stamped copy as a receipt.
USA "lettermail" does not have the same size/weight restrictions that Canadian Lettermail has. Basically anything up to 4lbs can be sent lettermail (there are some maximum size restrictions but they are rarely relevant unless you are shipping feathers. Canadian lettermail can be no thicker than 20mm/2cm.
Ben

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915

"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915
- answering Trolls is voluntary, my policy is not to participate.