There is no evidence of tornadoes on Jupiter. The Great Red Spot has sometimes been compared to a tornado, but in reality its dynamics are completely different.
TORNADOES
Tornadoes can happen in any place that gets thunderstorms.
Tornadoes happen every year.
No. There are enormous, magnetically-driven vortices of plasma on the sun that have been compared to tornadoes. However, these are not true tornadoes as they operate on entirely different mechanics.
No. Mercury has essentially no atmosphere. There are no storms of any kind there.
There are no tornadoes per se on Jupiter. There are however very violent storms there, stronger than anything on earth. These storms have more in common with hurricanes than with tornadoes.
Tornadoes happen in Miami for the same reason they happen anywhere else. See the related question for how tornadoes form in general.
Tornadoes happen in Africa because of the mountains they have or because of the weather.
Tornadoes can happen in Ottawa. Canada does get tornadoes, though not as often as the U.S. due to its cooler climate.
The term you are looking for is tornado watch.
Tornadoes can happen anywhere in the world except cold areas like Antarctica and the north pole. Tornadoes are mostly common in United States.
Most tornadoes in the U.S. happen in spring and early summer.