Questions about Copyright Assignment

[metal alpaca]

Hello, I have a few questions regarding copyright assignment:

1 ) Do I have to get my school/employer to sign anything?
2 ) If I change schools/employers, will I have to redo the whole process?
3 ) If I add a package to ELPA, then change to a school/employer where I’m no longer able to assign copyright, then would I no longer be able to push changes to that package?

Thanks!