Goku: As he was right after the beam struggle with Vegeta.
Nappa: With the power he showed when he was knocked around during the greatest part of his fight with Goku (regardless of whether you believe it was his full power).
Remember when Vegeta learnt how to sense chi just by watching the earthlings do it? What if, during his first visit to Earth, he had also learnt Kaioken in the same manner?
Rule: Vegeta realizes that only after leaving Earth, so it does not affect his fight with Goku.
Let's say he had decided to listen to Kaio's advice and just take his friends and leave Namek instead of messing with Freeza.
Here is what I think would have happened...
Goku offers to take Vegeta to Earth too, which he accepts, since, in canon, when he thought that Freeza had obtained...
From now on, I want you to call me Hector. I'm no longer afraid of having a proper username. Let's open the door to the bright corridors of the future together.
Let's say that, when they woke up, in Trunkses timeline, they decided, instead of just brainlessly killing and destroying, to overthrow the king and rule the planet.