Test Yourself on “einsetzen”

What’s the MAIN meaning of “einsetzen“?

“einsetzen” can also be used with a self reference, like in this sentence:

“Maria setzt sich für Eichhörnchen ein.”

But what does it mean?

The noun for “einsetzen”  is “der Einsatz“? What’s the right translation?

At the meeting, the manager demands “mehr  Einsatz” from the team. What does she want?

Wait, what was the gender of “Einsatz” again?

After a long day of work at work, you see a really comfy couch. What do you want to do?