Item 1 is documentend in SecureKnowledge. The exact procedure is listed there based on from where to where you are going to migrate.
Item 2 varies a lot. As I can schedule it and plan my work ahead I can do this propably within an hour or two if I can prep this correcty. Depending on how large the rulebasses are. But I would forecast 4 hours as a minimum.
However worse case scenario's mean you haven't tested stuff and need to roll back after spending a few hours trying to resolve things
As it stands R81.20 imports require a custom hotfix at the moment if you have multiple gateways with variations on the exact blades active on each firewall. I expect it will be rolled into the next GA Jumbo Hotfix.
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