Traveling to Canada
If you come from abroad and do not have a U.S. passport, you will need either an Electronic Travel Authorization, if you are from a visa-exempt country, or a Temporary Resident Visa. You should check with a Canadian embassy or consulate to see whether you need a visa to travel to Canada. Also note that if you have a non-direct flight with a connection in the U.S., you might need a U.S. Visa.
Airport to/from Downtown
A large number of airlines fly to Montreal and the Pierre Trudeau International Airport (YUL). The 747 Express Bus provides transport to the downtown area (near the René-Levesque or Berri-UQAM metro stations) in about 45-60 minutes. The ticket includes unlimited free public transportation for the following 24 hours ($10), 3 days ($18), or week ($25.75). Taxis are available just outside the terminal and cost $40 plus tip to the conference venue; if you need to pay by credit card, check with the taxi driver before getting in. The Uber app also provides pick-ups at the airport; you will need to go upstairs, to the departures gate. It is usually a bit cheaper than a taxi, unless there is surge pricing.
Directions from the airport to the venue: https://goo.gl/maps/YbEMRu22z2M2
The metropolitan Montreal area provides a large selection of hotels, pensions, and other accommodations in all price ranges.
The list of hotels that offer deals for McGill-related events, together with booking instructions, is located at: https://www.mcgill.ca/accommodations/mohp/downtown. In addition to those, blocks of rooms are being held for the ISMA attendees until 4 May 2017 at the following McGill University residences:
Single or Double $124.00 (breakfast not included)
Royal Victoria College
Single $45.00 (breakfast not included)
Single or Double $115.00 (breakfast included)
The rooms must be reserved by 4 May 2017, after which the hold will expire. Individuals will need to make their own reservations, as detailed in the above links.
There are a large number of reasonably priced housing options available in Montreal. You should be able to find a 2- or 3-star hotel for under $80 / night at venere.com or booking.com, or someone renting out a spare room on airbnb.com for a fraction of that (the cheaper options cost between $30 and $50 / night).
More information about the city offerings (transportation, restaurants, etc.) can be found here.