How common is it to have both a hurricane and a tornado at the same time?

[Metaphorical]

8. A tornado is a a turbulent vortex

Hurricanes are very low pressure turbulent systems. and just like eddies in rivers, usually occur along the edges where the winds encounter some kind of obstacle. Most of these tend to get disrupted before they become large enough to build a centralized "eye", but with a high strength storm, these eddies are spun off rapidly enough that they gain a certain degree of cohesion. It's usually these, rather than straight wind from the hurricane itself, that does so much damage to roofs.