Greetings,
Mr. S. I am somewhat familiar with Kingston to Iroquois and Saint Anne de Bellevue to Tadousac. Kingston to Iroquois is a straight forward run that goes through the Thousand Islands. Very pretty but be aware that IF you stay in the main shipping channel you will be in US waters for a period of time and IF you have any problems and have to go ashore you WILL need your documents (passport etc.). IF you do not intend to stop, have problems or anchor, you're fine to navigate the seaway with minimal documentation.
An alternative is the small craft channel which is north of the shipping channel and completely in Canadian waters. Quite a few marinas and towns along the way.
You will have to transit 6 seaway (commercial) locks. We've only done the two last locks (Cote Ste Catherine and St. Lambert). Best to have at least two on board to handle lines. Preference is given to commercial traffic so be prepared to wait or share. Once past St. Lambert, you're open to the Atlantic. From there it's about 190 miles to Quebec City. Past Quebec City there are fewer marinas and I only remember 2 between Quebec City and Tadousac (only familiar with the north shore-there may be others on the south shore).
Most, if not all towns and cities will have marina facilities with diesel available. Past Trois Rivieres you will have tides to contend with which probably won't affect your speed much but IF you can work the times, an outgoing tide can, in certain areas, add as much as 7 knots to your speed over ground.
Only got as far as Tadousac so you're on your own past there, my friend.
