I can help you sort this out because I've had a couple conversations with the US CBP and Canadian customs folks about this when I have said my visit is for business reasons.

Most certainly your laptop (and misc sundry like Mifi routers or a personal hub you might need for your own use, regardless of who actually owns it) is not a commercial good.

Most certainly samples are a commercial good and you cannot use Nexus when you have them, though occasionally this gets overlooked (though you risk losing your Nexus card). If you're for example mailing a package to someone you sold something over the internet to (like through ebay) it's commercial goods.

PhotoJim, what you are doing IS business, even though you are not compensated. The purpose of the trip is a business related thing (even though it's non profit). Whether or not you are being paid is irrelavent. If you were being paid, then you might get denied entry without an appropriate work visa.