u/Able-Winter4110

Hi everyone! I booked a ticket from Tokyo to Newark, NJ with a connection in Montreal, but my plans have changed and I need to go to Paris instead of Newark.
My ticket is non-refundable, and I’m thinking about booking a separate flight from Montreal to Paris, since that seems to be the cheapest option.
The U.S. is home for me, so immigration or visa issues related to entering the U.S. aren’t a concern in my case.
I have two questions:

1. Can I skip the Montreal–Newark leg of my original itinerary, or could that cause any issues?
2. What happens to my checked luggage? Is there any way to have it checked only as far as Montreal so I can collect it there instead of having it sent to Newark?
   Thanks!