Upload & Sell: On
I get lots of stuff shipped from sellers in the US to me in Canada.
1) Tracking depends on the shipper and/or service selected. I think you can get delivery confirmation (which is what really counts) for both USPS International Priority and USPS Express Mail. As a recipient, I prefer International Priority. Courier services offer delivery confirmation and usually very accurate in-transit tracking.
When offered, USPS tracking sometimes has a long-enough time lag that the package can arrive at the destination before the tracking app shows that it's even left the US (same for Canada Post - CPC). No worries about delivery confirmation though.
One thing to avoid is having the package left on somebody's doorstep. The delivery service will confirm delivery, but the buyer might not actually get it, if somebody swipes it. This can be avoided by requiring a signature for accepting delivery. This increases the cost by a few bucks, which I think should be paid by the buyer.
For cross-border items with value over $1000, I always require the buyer to pay for shipping by a courier service. This is because CPC has a maximum of $1000 for cross-border insurance coverage. USPS may have a higher limit for US > CA, but it's something you should check, if the item is expensive.
2) As above, "additional costs" vary with the shipper and/or service selected. In all cases (unless the buyer refuses to accept the delivery), these costs are IMO the responsibility of the buyer. Make sure they understand this. These costs can typically include a handling fee, a brokerage fee, and local sales tax. There should never be any duty payable on used cameras and lenses, although there could be for accessories like tripods, lighting, and etc. The size of the handling fee/brokerage fee varies incredibly.
For USPS, the handling/brokerage fee and local sales tax are collected by Canada Post (CPC), unless they're not collected at all, that is. USPS/CPC is especially attractive for the buyer, as virtually all packages with declared value less than $100 just get delivered - no extra fees (it's not worth the cost to USPS/CPC to complete the paperwork). I've had items up to $700 declared value delivered to my mailbox, with no extra fees. I've also had many items with values from $200 to $500 for which I paid the fee and sales tax. No worries, that's the way it should be. No extra fees is a bonus that you can only get for postal shipping.
The USPS/CPC postal service handling/brokerage fee is modest, usually $5 to $10. Shipping by courier (UPS/FedEx) can be a very different matter. Shipping by Ground is least expensive for the initial cost, but the brokerage fee can be ridiculous, especially for UPS Ground. Shipping by courier always invokes at least some brokerage fee (average probably $30), plus local sales tax.
I sent a Canon 300/2.8L IS by courier to the US late last year (to an FMer), and it was refused because of the additional $200+ in 'extra' fees. I explicitly warned the buyer to expect this, and I even told him the estimated the cost quite accurately, but if he won't pay, then back it comes. I think he got cold feet and did this as a 'painless' way to get out of the deal. I wasn't home when the shipper returned it, and they actually left it on my doorstep (value $4000), but that's a different story (suitable FM whiner thread was posted).
As the shipper, you have to fill out a customs form that identifies the package contents and value. In order to get appropriate insurance coverage, the declared value must match the insured value. Don't skimp on insurance. IMO, the cost for insurance should be paid by the buyer.
For the first few times, you're probably best off to take the packed item to the post office, and get an all-inclusive cost estimate. Then clear this with the buyer. Note that this will not include any handling/brokerage and sales tax fees that might be imposed later. Don't forget to mention this to the buyer. I've done this a lot (CA to US), and I'm confident with using the CPC online cost estimating apps.
P.S. it's a lot easier to ship from the US to Canada, than the other way around, especially for DSLR cameras over $1000 value - you have to complete commercial import and FCC electronic interference forms, for goodness sakes!