Unless it was changed inheriting(not integrating) an elector nets you their title and is really the only way besides starting as one of few nations, getting close to the Emperor while killing off electors and hope they pick you.One can hope you get that electorate, I think the Emperor just gets another electorate to appoint at that point. And I don't think you can appoint yourself an electorate, that might be too gamey.
Yes. That is called inheriting and works along the PU mechanic, every time a ruler dies and would create/continue a PU there is a chance of inheritance based on shared culture group, size of the minor, diplomatic reputation and stability of the senior. You should have become an elector of the HRE unless they lost it somehow or Paradox changed things.Okay. Even though it's a bit late I RMed Bohemia.
Then the ruler dies without an heir and all Bohemian lands got annexed to mine (Poland). Is this normal?