If you're really committed to leaving I suspect it would be better to do so, and get settled, in advance. Instead of on the flag-day when "everybody" else is also leaving.
Moving countries isn't easy, and getting settled in a new location takes time.
It's already too late in most cases, getting permanent residence rights elsewhere in the EU requires you to have lived there for 5 years; but there's under 2 years left before UK citizens lose their rights to work elsewhere in the EU. So you'd have to emigrate as a non-EU citizen, unless you qualify under one of the get-out clauses (eg joint citzenship, or you go to work in the EU and then have an accident that prevents you from ever working again(!))
No, that is not necessarily the case. It will depend on the outcome of the negotiations.
The 5 year rule is part of the existing freedom of movement regulation. It provides additional protection against getting kicked out in case of sickness or unemployment.
Exercising the right to live and work anywhere in the EU before Brexit takes effect may well mean that you can keep those rights after Brexit and acquire permanent residence rights later on.
Anything else would mean that hundereds of thousands of people would have to be deported, which would go against every promise made in the referendum campaign.
The UK is still currently member of the EU right now, so there's nothing stopping you from relocation.
From there you might have to wait N-years for citizenship, but freedom of movement hasn't been curtailed at the moment, even if it might be in the future.
The only potential spanner in the works is the question of what happens to foreigners in the UK, and the reciprocal agreement that has yet to be agreed. But it seems extraordinarily unlikely a UK-citizen who gained residency in German would be told to leave in two years time.
Moving countries isn't easy, and getting settled in a new location takes time.