There a few good indoor clubs; as Kick_it mentioned there's Iles-des-Soeurs, Cote-des-Neige, Tennis 13, and Jarry park, where they play the Rogers cup outdoors, but they also have indoor courts. Also Jarry is not a private club, so there's no membership, only court fees.. it can however be hard to book a court at times, since you can only do it 48 hours in advance, an the place is pretty busy. The others I've mentioned all have membership fees + court fees, but the court fees can be small or even free, depends on the deal you sign up for/time of the day you play.
Otherwise, for tournaments, just have to find out from each individually. They have leagues, but I dont know any details about levels etc... there're always 2.5-3.0-3.5 leagues around, though. I have seen some higher level league play, though, but I dont know any details. Cost depends very much on the place, but maybe membership fees are on the order of 100$ a month. Jarry park charges ~30$/hour per court at normal hours, and cheaper early in the morning.
In any case, you can find a lot of information about these clubs and others from websites, so google it.
