Lightning Surge Suppressors already exist on essentially every high voltage line and significant transformers in the US.
Yep. They just need to be a bit more robust for a large EMP event.
Were also need to add more surge suppression to the lower voltage local lines and for individual equipment and end users.
No need to upgrade existing consumer stuff, just make new stuff with intrinsic protection, product life cycles will insure that within a decade or so essentially everything will be protected.