It is very likely that most of your satoshis have been in a mixer at some point.
Yes, but government has special magic trick to make any bitcoin sats whitelisted, and than they can sell it

If anyone else tries to do that they are going to be charged as criminals.
Exchanges can't check the complete history of every sat. They will probably check the past 3-6 transactions...
They are obviously not doing anything manually.
Analytics software used by them is complicated and it is checking all connections, not just ones that are previously made.
I think this is all crap,it is not exact science, and it's dangerous for Bitcoin.