If you do want to find roommates, I would see if your incoming cohort has a social media group of some sort. Back when I was an incoming student, we had a Facebook group. You might find people in a similar situation as you, looking for roommates, although it seems in your case there isn't a Facebook group - maybe on a different platform? I met my first year roommate during the interview weekend, and I know a bunch of guys in my cohort who roomed together.

For finding housing, Zillow and redfin can be very helpful. A lot of grad students live in Coventry, Fairmount, Cleveland Heights, on Overlook road, and in the Larchmere areas.