Personally, when I first came to Canada I bought a used vehicle from a guy in town - I found the car through kijiji (or craigslist) and felt it was a good deal. I paid $1600 for a ten-year old car, that was driving and served me well for a year, until I got hit and had to write it off.
The process of insuring it was very easy! Mind you, I lived in British Columbia, so that's all I can talk about:
I bought the car and we drove it straight to an insurance office (there is only one car-insurance company in BC: ICBC - all insurance offices deal with them), were we did all the paper work together with the insurance agent and they gave me brand new plates and explained everything I was getting for the money I was paying. I left half an hour later and the car was 'road-safe'.
One important thing to mention: The price you agree on in a private sale does not yet include taxes. You have to pay taxes when you sign the car over to it's new owner (the buyer has to pay, never the seller!) at the insurance office.
I also went to a dealership this year to possibly buy a new car: beware! Car dealers have a bad reputation for being shady. I got hit with an enormous interest rate, which was not reasonable for my credit rating nor the current trend in interest rates. This ultimately made me walk away from the whole thing.
But to give you an idea: We agreed on a price around $15'000 - at the end of the day, with their 'filing fees' and 'bank fees' and what-have-you the car would have cost $22'000 + an interest rate of around 14%.
Be specific about what you want to pay and know that the interest rates they give usually have their profit-margin built in (meaning: that is where they make their money!).
The dealership usually has insurance brokers there that will get you on the road the same day you sign the papers. Beforehand however a credit check is needed to purchase vehicles which takes a few days.
Depending on your vehicle expect to pay around $100/month for insurance - for bigger, newer vehicles it would be more; for smaller ones less (and again: this is in BC! I heard Alberta is a lot cheaper). The amount also depends on how long you have been driving accident free! And this means since you first got a licenses, however you have to bring proof that you have had vehicles insured in another country and have not gotten into an accident, if you want your previous driving record (outside of Canada) be taken into account. Any insurance office can tell you what information is needed exactly.
In any case when buying a car: haggle! Always worth the try. And (when buying private) come with money in hand. Cash always makes people more willing to accept a deal