If invited to a business meal in Canada, it is most likely to be for a lunch or possibly a breakfast meeting. Although it is not unknown to be invited out for dinner, it is less common than in some other countries.
It is not really considered impolite to discuss business issues over the meal. It is relatively unusual for alcohol to be served with a meal at lunchtime.
When eating, the fork is held in the right hand and is used for eating. The knife tends to be used to cut items or spread things onto a food item. When using your knife, the fork is switched to the left hand or is laid down on the plate. When you wish to continue eating, switch your fork back to the right hand. (You can, of course, use the European style of dining, in which the knife and fork are never switched if that is what you are more comfortable with.)
Restaurants charge a Goods and Services Tax [GST] but gratuities are not included in the bill. It is expected that you leave a tip of around 15% for good service.