I just got back from a trip to Baltimore. I'm not from there so I have no local knowledge but from driving around it looked like there was a lot of good cycling areas (road and off road) around BWI Airport. I also drove the Chesapeak Bay Bridge and it looked like there were some beach clubs along the coast there for OWS. Sorry I don't have more specifics but it might be a good place to start.
Towson is going to be rough because of traffic and the roads around there are just not suited for riding. Depending on what part of Towson you live in (near the city, near the university, towards timonium?) you might have to travel a bit to get to some good low traffic roads. Check out some LBS in the area for rides and sometimes they have routes listed. I know up here in Harford County, we have plenty of good routes to ride and if you google bel air bike shop, they have several rides listed with turn by turn direction and elevation profile. Also check out local tri clubs as many have weekly group rides on the calendar (Harford Multisport, Mid Maryland Tri Club, Baltimore Area Triathlon Club, Annapolis Tri Club). As for OWS, check out the clubs and see what they do. I know my club (harford multisport) does OWS at a club members house which is located on a river. Not sure about other clubs or places in or around the towson area. You can PM me if you have any other questions.