Since the vast majority of founders fail, having significant financial cushions from your family or years working prior is probably the top pre-requisite if 'founder' is your path.
This may or may not apply to all locations and all collapses, but expect collapses to happen every 8-10 years.
I'm also not all that certain that down markets don't hit all categories with similar force. Contractors may be cut slightly earlier (discretionary spending), but that depends on contracting terms and duration (there are set-length contracts), and as a bonus might be hired back earlier.
Much depends on whether or not you have a specific skillset that's in demand, and know how to market it effectively. And that's regardless of your employment terms.
Sure, but during an economic contraction is typically not a good time!
If you're a valued contributor and your client is aware of that, they may be able to swing things. That may end up being a zero-sum game, with existing headcount being eliminated. Much depends on the organisation's own policies and savvy.
It's an argument for maintaining good relations, though.
Contractors can save many more multiples of cash than employees in the same period of time between collapses, assuming they have some discipline.
Discipline contributes to freedom more than anything.