I’ve crossed over to Ontario from NY 4 times this past year, all of them quick and uneventful. I also crossed over to Montreal last year, also uneventfully.
If you want to be sure of proof of insurance while driving, call your insurance company and ask them to send you the card that you need for Canada. I’m looking at mine right now; it takes them 5 minutes to fill it out and email it to me. The heading on it is
Canada Non-Resident Inter-Province Motor Vehicle Liability Insurance Card.
Montreal is a very cosmopolitan city that gets lots of tourists, and almost everyone there is bilingual, some people speaking English, French, and a third language from their ancestral homeland. Quebec City perhaps somewhat less so. It’s the rural areas of Quebec that tend to be more insular and whose residents may only speak French.
I drove from Canada to the US this evening with no trouble.
My experience is that everyone in the tourist trade in Quebec speaks English. And they speak it very well, they don’t just know enough English to conduct routine tourist transactions. Also, Google translate is really good these days. I never needed it in Quebec, but i used it from time to time when i visited Italy earlier this year. (And i actually heard more people speaking French when I was in Ottawa a year ago than in Quebec City this summer.)
Is it polite to learn some of the local language? Of course. But unless you enjoy eavesdropping on random people near you, an anglophone doesn’t need to know French to visit Quebec.
Same experience here. Everyone we encountered in Montreal and Quebec City spoke English – usually as a first language. I always engaged in French, but no one minded using English.
One tour guide made a point of dispelling the myth that some people will ignore you if you speak English. He said the same as @wolfpup – you have to get into the rural areas to find many French-only speakers.
We got back yesterday and had no issues at the (airport) border crossing. During our stay, tariffs and immigration came up in conversation, but always in a very polite way.
I cross back and forth by car multiple times a year at a number of different Vermont crossings, as well as the Rouse’s Point crossing in NY (never crossed on I87).
So far I have not noticed a meaningful difference (white US citizen) in recent years.
As far as bringing things back and forth… I’m sure there are explicit instructions you could search. I often declare something like “we’re bringing back a few groceries and snacks, some small souvenirs, some books (or whatever),” and we’ve never had a problem, nor had anyone even ask to look at things (though it does happen).
The funniest time I had crossing the border was one time I did it while I had some board games in the back of my car. (Nothing related to going to Canada. I just had them in my car and hadn’t taken them out.) The border guard who saw them called over another border guard, who apparently was a board game player. This second guy spent fifteen minutes looking through the games in my car and asking me questions about what I had played.
If your trip is really a “day trip” (less than 48 hours) then you can bring back up to $200 in goods to the US without incurring any customs duties. Your ability to bring back alcohol & tobacco is also limited. If you stay there for more than 48 hours, the exemption goes up to $800.
Yes, just what I was going to say. OP says he is going to Montreal. If he’s planning a drive to, say, Abitibi-Témiscamingue, a few phrases probably won’t cut it.
I once crossed into the USA with a 1/2 scale 4 foot model missile in the back seat. Border guard said to me: “You gonna fly that?” I said “Yep”. He said: “Did you bring the rocket motors with you?” I said “Nope, I arranged to buy them at the launch field”. He said “Have a good time.”
I know a few years back, there was a strict ban on bringing any beef from Canada into the United States. We used to go up to a meat market to buy smoked beef and they would label the wrapper as “pork” so you could take it back across the border.
Getting back into the USA is no problem if you are American. Anything else, results can be unpredictable. Generally, Canadians have no problem. But as the example upstream notes, having a residency permit of some sort for the USA means you better be really sure things are OK. I read of someone with one of those special visas for technical employees, years ago, who went home to Vancouver and was told he could not re-enter. Even though he was a highly qualified IT Telecom expert, apparently the border guard told him "only for people with university degrees, being qualified with experience doesn’t count. Once one says “no” it’s a lot of paperwork to (possibly) get reinstated.
One thing I read, not sure how true. You can use the NEXUS to go through the express line. But… if you pull up to the border, then a passenger gets out on the Canadian side and walks across in the pedestrian crossing to meet you on the other side (because they don’t have a NEXUS card) that too can be grounds for confiscating the NEXUS card.
Another fun fact - dual citizens apparently must enter the USA on their American passport. There was the story of the Israeli whose parents were working in the USA when he was born. He flew into NYC for a conference as an adult, and was sent home because he only had an Israeli passport. (Not sure what documentation you need to show you fully renounced your US citizenship).
It’s apparently quite involved. My friend is in the process of doing this.
Just a single instance I’m aware of, so grain of salt, but there was no issue or even a question.
Another fun fact I read was that those who renounced their citizenship are only allowed to visit the USA for (cumulatively) 1 month a year. You don’t get to say “buh-bye” and then spend up to 180 days a year enjoying the old home.
My parents renounced their US citizenship 2–3 years ago, retaining their Canadian citizenship. I’m fairly sure they’ve spent more than 1 month per year in the US since then visiting family members in the US including me, though not much more than that (less than six weeks.) So either this is inaccurate, I’m misremembering the amount of time they’ve spent in the US, or the USCIS panopticon just hasn’t noticed them yet.
The main problem is that Canadians are so friendly that you might not want to return to the USA 
I remember reading this years ago, when the USA changed the law to make banking difficult for Americans abroad; but I see no evidence of it searching now, so apparently the same rules apply as any other foreigner.
I found one refeence to the Reed Act, which allows the USA to bar entry if the person renounced citizenship to avoid a large tax liability - but this has (almost?) never been applied.
Terry Gilliam is a prominent example. He was born in the United States and was an American citizen. He acquired British citizenship in 1968 and held both. He renounced his American citizenship in 2006 and since then he can only legally be in the United States for a maximum of thirty days each year. When this story occurred, some noted the irony that other members of Monty Python, who were also all British citizens, could reside in the United States as long as they wished.
I went to Vancouver for a lunch date on Tuesday. It was the shortest interaction on the NEXUS line ever. I had the drivers side windows rolled down. Agent said “anything to declare?” “Nope” “have a nice day”
Not even the standard “do you have a firearm?”