First your question about bringing your computer on board, yes You can bringing on in addition to your carry on bag. Everyone is allowed a carry on plus a business bag.
Unfortunitly Air Canad does not have internet on board the plane but they have free WIFI at Pearson now.
Have you ever flown before? EVERYONE has their laptop on board. Don't ever put your laptop in checked baggage. Same with cameras, cell phones, valuables, etc.