Coachseats, you are beating me to the draw(though I took the trip 30 years ago, details understandably a bit hazy). I am going mid-September.
You need to check with Via Rail Canada's website and that will help.
1.As to food across the border, I suggest you call VIA (1-888-VIA-RAIL) and ask. They are NOT a 24/7 operation, rather, that phone is answered from about 7 a.m. to about 11 p.m. You could possilby ask the same question of Amtrak, as to border crossing.
2.Drinking water, sure, just like here. In many, many respects their facilities are very similar to ours(see below question 6).
3.American dollars on the train? Probably. When I have been to Canada before, not just the big trip but shorter, I SEEM to recall having no trouble with American dollars, but again I would ask. Since you will be seeing those people (on the train) for several days, Canadian dollars might make you more welcome, But call and ask.
4 How long the stops? Check the internet post or call and ask them to mail you a timetable. Some of the stops are quite long, actually.And there is quite a bit of padding in the train's schedule, I have read. You can probably pick up a timetable at the station or onboard, if not before. They will probably make good announcements about such things.
5.Photo ID and original birth certificate good enough, Yes, I think so, Amtrak timetable goes into this.
6.Major differences? There are a thousand ways to answer this, and with how much detail, etc. There is also a potential generation gap here(because this is well maintained equpment from 1954 as opposed to Amtrak's much newer equipment). ......so.....let me answer it this way.
FIrst, this equipment is the same kind, inherited from the railroads when Amtrak was formed, which came to be known as "heritage" by Amtrak. Still found in the east on some diners, dorm cars, baggage cars. It does not bear that name in Canada, no need.
Superficially, it will still look like our trains (though built in 1954, it will not look like an "old wild west" steam engine type train---it will still look good....very good) and it will be silver(as we are used to here). The equipment corresponds to our single level in a way, not to Superliner. But instead of double deck superliners, there will be a few "dome cars" scattered about consist.
Domes are camel hump protrusions sticking up from the roof of a few cars. There are 24 seats in a standard dome. The dome car is something you visit on your own, like the diner and lounge, if and when you wish, assuming seats are available. It is not reserved space, it is public. Though it is possible that, as a coach passenger, you will not be allowed into the rear dome,which is also an observation car.("observation" does not refer to the dome, it refers to the rounded rear end of the train with windows to look out. THOSE kinds of cars were invented many years before domes, thus the name "observation" became attached to them; first come, first served.
Our Amtrak Superliners have the advantage of the entire train being double deck, so you can see well from your room or your seat, as long as you are on the top floor. On "dome " trains, not so, you have to "go'" to where the viewing is good. One advantage to a dome, though, is that you can see straight ahead out of its front window. Look at the VIA website and you will see domes. (and also the Observation car).
If you were riding in a sleeper(and I know you are not) there are different names and types of rooms from what we have in Amtrak.
In a coach, I cannot think of any serious difference. Of course the shape will be a little different from, say,Amfleet II. It will be bulkier, boxier, less streamlined, the entire train will be that way. I think you will find larger restrooms, with sort of a lounge area within them.
The diner will be familiar looking (like a "heritage" diner). Lounge space will be kind of different. It also has some coffee-shop lounges, which will be slightly different from what we are used to on Amtrak.
Again, there are many ways to answer question 6, let us know any other questions.