My unsolicited advice - having done something similar with drupal though, not wordpress - choose something you'll enjoy working with, if it's wordpress, go with it (keep in mind there are a lot of "wordpress" developers and by that i mean, people who just grab a bunch of plugins, put a site together and say they have extensive wordpress experience - don't be that person). That all said, you may have better luck with a framework like rails, django, etc. if you want to make a similar transition into product building...

From there, get involved in the community (e.g., attend meetups, drupal has a good one in toronto). I found success finding clients by learning about drupal and recording video tutorials about what i learned to teach others (drupal has a ridiculous learning curve when you are coming from no where).

Hope that helps.