Live or Dead ball after kick

[Bigdawgg65]

I need a little help with clarification using NFHS rules.

This has happened in a couple of different ways:

At a kick off or punt R catches or picks up the ball with a knee on the ground. Is this dead at the spot of the catch or pickup?
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At a kickoff R muffs the catch at the 1 and the ball rolls into the R end zone. Can R run the ball out?
Or
Is this ruled a touchback because the ball broke the plane.

***
Punt from the Ks 3 yard line for the 4th down.

Ball is poorly kick and lands 1 yard past the line of scrimmage in R NZ. The ball makes contact with R lineman, who is oblivious to the location of the ball, and the ball bounces back over the line of scrimmage and is picked up by K and run for a forward gain of 3 yds but not past the fist down marker.

Who's ball is it ?