[CoenceLomneedtrue]

Born and raised in Montréal, but moved away in 2001 and have not attended a GP since ( ).
I have only ever purchased the Silver tickets at the hairpin.

Yes, the Metro is great for getting around, including to the venue, but be prepared for a time consuming walk from the station to your grandstand. Although not a long distance, it does take a while amidst the throngs of people.
Hotel accommodations for the race weekend sell out quickly so best to book early. Anywhere near downtown will be hideously expensive. An option would be to find a hotel outside of the downtown core but access to the Metro may then be difficult, so you may want to budget for taxi fare from hotel to Metro, or even directly to downtown.
A more expensive option would be to rent a car for the w/end, but parking downtown is not only a nightmare but pricey.

During the w/end definitely check out Cresent Street downtown!

Feel free to PM if you have any specific questions