OK, I just arrived in Montreal (at my hotel right now) and I can report the following:

(1) My first use of NEXUS, and it ROCKS! The only problem was that one machine was out of service and the others' touch screens were COMPLETELY WORN such that one didn't respond at all to the "English" prompt, and the one I finally did use required pounding on it in order to get it to respond. But once that was overcome, 45 seconds and you're DONE. AWESOME. Worth getting if you travel through major Canadian ports of entry AT ALL (I only pass thru once every year or two, and still worth it!)

(2) RBC ATM next to the Currency Exchange in the Int'l Arrivals Hall was SO SLOW that it took the 2 guys in front of me in line at least 8 minutes each for a simple withdrawal, and then in my case the PIN entry was so slow that I screwed it up twice and finally gave up. However, the nice gal at the Currency Exchange told me (us) that there is indeed another ATM or two up the escalator in the Ticketing/Departure lobby, which I used and which took 30 seconds. Now I've used the downstairs ATM with no problem on previous visits so I dunno if today was an aberration or not, but in any case this new intel about alternate ATMs right upstairs is important/useful.

(3) The 2 Metro ticket machines are indeed within plain sight in the Int'l Arrivals lobby. I used the intel gathered here and didn't even bother to try my USA-based credit card...I just paid cash to recharge my OPUS card with a 3-day pass for the duration of my visit. I was then on my way to my hotel via its courtesy shuttle.

Hope this is all helpful info.