First full year working on a TN in the US - 3 questions

[Kever]

Context: I have a TN visa . I worked in the US 5 months in 2017, and 2018 was my first full year in the US. I own a house in Canada, and have a wife and 2 kids who live with me in the US.

Question 1: My wife earned a small amount of money for a consulting job in Canada while we were in the US at the start of 2018. Would it be best for us to file as "married filing jointly" in this instance? We realized after the job that she wasn't supposed to work, but I'm unsure about how to file since we learned this after the fact.

Question 2: We're currently renting our house out in Canada. I'm assuming we file any rental income from the house in our US and Canadian tax returns, correct?

Question 3: Last year we filed as Canadian residents, as we spend more of the year in Canada. Now that we're filing as US residents, are their major impacts we should know about in terms of owning a house in Canada? We've already divested of our other investments, so that's not an issue. We also had our house appraised the month that we left Canada. Is there anything else we should be aware of?

Thanks for any help and guidance you can provide!