Does a power of attorney designation end upon death of the person who designated that power?

Yes. Power of attorney is only relevant to the person who designated that power. So they have to be alive. The nature of their will, and its executor, then takes precedence.

Yes

Yes indeed!

Yes. POA exists only over a LIVING person.

Yes. Always.

Of course. You can't sign for a dead person.

It depends on the language of the PoA papers, but it often carries on to include PoA over the estate of the deceased.

No. You have to be buried with the deceased.