4th & 5 for K at K's 30 yard line, While the ball is in the air across the expanded nuetral zone, (1)K2 trips R3 or (2)R4 holds K3, R1 muffs catch and K recovers at R's 35. How do you admin penalty? Also what if R recovered?

Not enough information in either case. In (1), where did K's tripping foul occur?

In (2), where did R's holding foul occur?

(1) K's trip occurred at 50yd line (2) R's hold was at 50 yd line

The requirement that R end the down in possession is not met here so we do not have PSK enforcement.
Therefore, the basic spot for penalty enforcement during a loose ball play is the previous spot.

Situation 1
If R accepts: 15 yds from the previous spot resulting in 4th & 20 for K at the K-15 yard line.
If R Declines: K's ball 1st & 10 at the spot of recovery.

Situation 2
If K accepts: 10 yards from the previous spot resulting in 1st & 10 for K at the K-40 yard line.
If K declines: 1st & 10 for K at the spot of recovery.

And to pick up your other question: If R recovers, then...

Situation 1
If R accepts: 15 yds from the previous spot resulting in 4th & 20 for K at the K 15-yard line.
If R declines: R's ball 1st & 10 at the spot of recovery (R35).

Situation 2
If K accepts: 10 yards from the end of the kick (R35), resulting in 1st & 10 for R at the R 25-yard line.
If K declines: 1st & 10 for R at the spot of recovery (R35).