Schaumburg is northwest (beyond O'Hare). Not sure about the bus. Is it a special that only goes to Wrigley Field? Or a regular suburban bus that will make stops along the way? Also, make sure you know the details about getting back on the bus, particularly if you want to go downtown to do things.
You may want to take a CTA train to downtown from near O'Hare, take a bus to Michigan Avenue to do your tourist stuff, and then transfer to another train that will take you north right to Wrigley Field. And after the game, take the train back downtown and then take the other train back to O'Hare.
Also, don't know about advance tickets for the boat ride, but it sounds like a really good idea. You never know when a group will walk up and take the boat you wanted. The boat tours are fantastic (and I don't think there is much difference between them). The history and architecture on a boat ride on a river whose current was reversed is fantastic.
http://www.pacebus.com/sub/espd/wrigley_field_express.asp