Right now, as you are just starting out, we would recommend you focus on ONE market at a time. There is absolutely great opportunity to expand into other marketplaces but it is important to first master one product in one marketplace at a time.
But to answer Q1/A2 – selling on Amazon.com and supplying Canadian customers is simply done by ensuring your global shipping setting in SC are set to include Canada. And the buyer in Canada will pay the extra shipping outside the USA.
SC > Setting > Shipping Settings > General Shipping Settings
(right now, your shipping templates will probably just be set to ‘Domestic Shipping’, like most sellers)
If you wish to launch in Canada you will need to send stock there and do a proper launch, just like you would in any other market, to get onto page one. So that requires time, resources, cashflow, and attention to also manage sales and inventory in 2 market places.
Q3 – Opportunity: Overall, the USA is a much larger opportunity and Canada is small in comparison, but it can be a good market for expansion of the same product when you are ready.
To assess the market opportunity, you will use JS data to review sales volumes and competitors on page one of your main KW on amazon.ca