We've done the Lynx bus from TTC to SeaWorld and it was quite easy. The bus number is #50, it leaves from the TTC at 18, and 48 mins past the hour. Arrives at SeaWorld parking lot at 39 and 09 past the hour...so about 20-25 mins or so.
DO be sure to tell the driver you are going to SeaWorld, we assumed others had told the driver (they hadn't) and we ended up hiking back quite a long distance back to SW. You should be dropped off right at the parking lot entrance, cross the lot and you'll be at the main gates. When you are ready to return, cross the parking lot, cross the street, and walk to the left. You should see a bus stop sign with the Lynx pawprint on it.
When you get to the TTC, be sure to get a bus schedule, then you can see what time the pick-up at the bus stop, at SW, for your return to TTC.