Yes. In some of the most intense outbreaks there have been over a dozen tornadoes on the ground at the same time, though not in the same place.
The record is 16 on the ground at the same time during the 18 hr "Super Outbreak" of April 3 and April 4, 1974. Total tornado count for the 18 hrs was 148.
They don't. While it is fairly common for a hurricane to produce tornadoes, most tornadoes are not associated with hurricanes. The thunderstorms that produce tornadoes may produce strong, even hurricane-force winds, but that does not make them hurricanes.
It is unlikely that two tornadoes could maintain such high intensity so close to each other.
It is entirely possible for two F1 tornadoes to merger. The resulting merged tornado would be larger than either of the original two tornadoes, but not necessarily stronger.
Tornadoes and twisters are the exact same thing.
Tornadoes occur most of the time between 3 pm. and 9 pm.
Tornadoes form in the southern hemisphere for the same reason they form in the northern hemisphere. The mechanics are the same. See the related question for what causes tornadoes
Yes, tornadoes can occur at any time of year.
Large hail, flooding, straight line winds and tornadoes.
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Yes. Tornadoes can occur at any time of year.