First of all, Gogeta is stronger than MUI Goku and Limit Breaker Jiren because Gogeta is made of Goku’s and Vegeta’s best traits and multiplies it by a lot so any power-up or transformation Goku or Vegeta gets is added to Gogeta. So how could Gogeta possibly be weaker than Goku? Gogeta is probably on par with Whis and Whis is stronger than Beerus.
As quoted in Pablo's answer, the Mortal Level is a measurement of the quality of the mortals used by the Kings of All. We're not really told exactly what goes into deciding this value, other than a singular data point from the manga (which did not happen in the anime, however, to my recollection):
We're also not explicitly told why this measure was ...
Agree. It's a mult, not a transformation.
However, it could have higher adverse affects when used on higher current powers. This is because a mult, is basically changing, what I see as, the per-second power output (i.e. power level). No matter what sort of power level Goku achieves, he has a limit on how much he can temporarily force that power output to be ...
There have been multiple instances where the Z Fighters have been shown living their normal lives such as
Gohan Going to School (After Perfect Cell Saga)
Gohan Visiting Bulma for His Great Saiyaman Costume (After Perfect Cell Saga)
Goku Farming When Mr Satan Comes to give him the award money he recieved after he claimed to have defeated Beerus in front of ...
Yes. Whis's statement is very clear. As far as others sensing his ki and what not, that's almost become a mute point. Broly, Jiren, 17 and Frieza don't have God ki, yet can sense and counter it just fine. Akira obviously abandoned this attribute for God ki.