Visiting Canada all in one trip is an ambitious endeavour. After Russia, it is the largest country in the world. When speaking of specific destinations within Canada, it is better to consider its separate regions.
Geopolitically, Canada is divided into 10 provinces (British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia, Prince Edward Island and Newfoundland) and 3 territories (Yukon, Northwest Territories and Nunavut.)
There are thousands of cities in Canada. These are some of the most prominent ones.
Canada is a land of vast distances and rich natural beauty. Economically and technologically, it resembles its neighbor to the South, the United States, and shares with it the longest undefended border in the world. Although Canadians are generally quite adamant that they are unlike their Southern neighbors, the differences are often subtle. They became a self-governing dominion in 1867 by an act of British parliament and retain strong ties to the British crown to this day. Though a small country by its population, Canada has earned respect on the international stage for its strong diplomatic skills. Internally, the country has never known civil war, succeeding instead in negotiating compromises amongst a culturally and linguistically varied population. In Canada's different regions, you will find as many differences as similarities. Language, culture, cuisine and even history vary quite a bit over the country. The information below will get you started, but be sure to check the specifics for given regions and cities.
You are likely to arrive in Canada by air. Probably in Montreal, Toronto, Calgary or Vancouver (the 4 largest cities, from East to West.) Although the citizens of many countries are exempt (most notably the United Sates and most European countries,) you may need a Temporary Resident Visa to enter the country. If so, you will want to consider a visa for multiple entries if you also plan to visit the United States. Working while in the country is forbidden without a work permit, although Canada does have several temporary work permits for youth from specific countries. The Government of Canada maintains quite an informative website for non-Canadians wishing to travel to Canada: http://canadainternational.gc.ca/
Although less likely, you might also enter the country by road or rail from the United States through one of the (literally) hundreds of border crossing points. Obviously, the same rules will apply here, but if your case is not straighforward, expect to be delayed, as the officials here (especially in more rural areas) see fewer international travellers than at the airports.
Canada is big. The best way to get around the country is by air. Air Canada is the main national carrier, but for travel between major centres, discount carriers like WestJet might have better fares. In general, airports are poorly connected to public transportation and railway transportation; expect to leave airports by road on a rental car, taxi or a privately operated bus.
You can also travel between most cities in Canada, small and large, by bus. Greyhound Canada provides much of the service, with smaller operators covering local routes. For some popular tourist routes, guided bus tours are also available. Of course, many people choose to rent a car. Although somewhat expensive if you are travelling alone, this can be an economically reasonable alternative if you are sharing the costs with others. However, beware of the high surcharges associated with dropping off the car at a different location than where it was picked up.
Passenger rail service in Canada, although very safe and comfortable, is often an expensive and/or inconvenient alternative. The corridor between Toronto and Quebec City is a bit of an exception to this generalization. In any case, making arrangements ahead of time (probably with VIA Rail, the main provider) is advisable in order to find lower fares.
English and French are the two official languages in the land, but other than in Ottawa, where a large number of people speak both languages, the bilingual nature of the country is generally expressed regionally. English is the dominant language in every province except Quebec, where French is dominant and actively promoted as the main language.
In Quebec, one can usually get by with English in the major tourist destinations, but some knowledge of French is useful off the beaten path, and almost essential in many rural areas.
See also: French phrasebook
The country's currency is called the Canadian dollar (symbol: $ or occasionally CDN$).
The banking system is well developed, safe and technologically advanced. In most cities, it is possible to convert between Canadian dollars and most major currencies at many banks, and they will probably do it for cheaper than at the airport. Even in the most rural areas, converting between Canadian and American dollars should not pose a problem. In fact, many tourist destinations will accept American dollars as such, but they are unlikely to give a very good exchange rate: you are paying for the convenience of spending in a foreign currency. Credit cards are widely accepted, with Visa and MasterCard being accepted in most places, American Express somewhat less frequently and Diner's Club only in the more upscale restaurants and hotels. Generally, using a credit card also gets you a better exchange rate since your bank will convert the currency automaticaly and usually at a good rate; the merchant does not have to worry about it. There is a safe and widespread network of bank machines where you may be able to use your bank card to withdraw money directly from your account at home, but the fees involved are often more than for credit cards.
Canadians themselves may laugh if you ask where you can get Canadian food. Although you will find some regional specialties, especially at the Eastern and Western edges of the country, there isn't really any food known as "Canadian." ... Except maybe for the lowly donut; it will be hard for you to avoid the "Tim Horton's" franchises spread across the country. They are an important, if somewhat humble, part of the Canadian culinary landscape. Why not?, since they will serve you a small and relatively healthy lunch for about $5. It is certainly a reasonable alternative to other fast food chains; you will find most of the American chains with a well established presence here. If you are more adventurous, in the larger cities especially, you will find a great variety of ethnic tastes from all over Europe and Asia.
Accomodations in Canada vary substantially in price depending on time and place. In most cities and many tourist areas, expect to upwards of $100 or more for a good hotel room. In rural areas, motels (for "motor hotel") are small, simple hotels where you might pay as little as $40 for a night's accomodation (especially in the off season.) Youth Hostels are a good choice in many cities; many are part of the "Hostelling International" group and meet quite high standards. Finally, there are a large number of campgrounds in the country. The publically operated campgrounds in National and Provincial parks are well kept and generally very beautiful.
Safety in Canada is not usually a problem, and some basic common sense will go a long way. Even in the largest cities, violent crime is not a serious problem, and very few people are ever armed (handgun ownership is fairly rare.) If you are unfortunate enough to get your purse or wallet snatched, the local police office (or any police officer) may be able to help. Often, important identification is retrieved after thefts of this sort.
You are unlikely to face health problems here that you are wouldn't face in any other western industrialized country. Furthermore, the health care system is very effective and widely accessible. In the past two summers, Canadians in some provinces (Ontario, Manitoba, Saskatchewan and Alberta) have faced a few cases of West Nile virus, an occasionally fatal infection transmitted by mosquitoes. Also, last spring, at outbreak of SARS scared some visitors into changing their plans, but since only visitors to hospitals in Toronto were ever at risk, it would seem that the fear was somewhat overblown.
The communication infrastructure of Canada is what you would expect for an industrialized country. In cities, there are many ways to access the internet, including a number of terminals at most public libraries. Cell phones are widely used, but due to Canada's large size and relatively sparse population, some rural areas have only analog service or no service at all. And, of course, there is always the postal system but although it is very reliable, it is not always speedy. Also, international postal services for parcels can cost a lot of money.