No, Canadian Coins are not generally accepted as legal tender in the United States.
US coins are worth more than Canadian coins. If you pay in US currency in Canada, the vendor makes money. If American vendors allowed the reverse, they'd lose money.
Yes, Canadian coins are generally not accepted for use in the United States. While some businesses near the Canadian border may accept them, they are not considered legal tender in the US. It is recommended to exchange Canadian coins for US currency before traveling to the US.
According to the Canadian Counsel they encourage the use of Canadian coin as well as US coins. The use of US coins makes no sense because it holds no value in Canada.
what kind of coin is it
Canadian coins are face value is the U.S.
There is no company that mints Canadian coins. The coins are minted by the Canadian government, not a company. The government entity in charge of minting Canadian coins is the Canadian Mint.
Yes, you can spend a Canadian dollar coin in the U.S., but it is not widely accepted. Many businesses may refuse to take it, as it is not legal tender in the U.S. If you do manage to use it, it would typically be at the discretion of the vendor. It's generally more practical to exchange Canadian coins for U.S. currency at a bank or currency exchange service.
They generally simply get spent as US coins. If the coins are pure nickel or plated steel (like most modern Canadian coins are) they will get trapped on magnets when ran through a coin sorter and then either exchanged for the equivalent value in US dollars by the bank/sorting company or given to employees/customers who are going to Canada. But the coins that aren't magnetic are simply spent like US coins as they have the same diameter and roughly the same purchasing power.
Canadian coins don't expire.
Yes, Canadian money is generally not accepted as legal tender in the United States. It is recommended to exchange Canadian currency for US dollars before making purchases in the US.
So that people can spend them and buy things to live.
Not usually. Unlike Canadian coins which have roughly the same purchasing power and diameter as US coins and are frequently found in change (chances are you have something Canadian in your change jar, especially if you live close to the Canadian border), Mexican coins don't follow the same diameter and purchasing power so except for towns close to the border where they are readily exchanged to US dollars (and you'd pay them in the exchange rate of Pesos to dollar) most places will not take Mexican coins in payment.