ok guys here is the first one thanks.

4th and 10 on K’s 45 yd. line and K1 punts. The kick travels beyond the neutral zone where it is muffed by R8. The ball rebounds back behind the neutral zone where it is recovered by K9 who then throws a forward pass to K2 which is (a) incomplete, (b) complete and K9 is downed at the 50 yd. line, or (c) complete and K9 is downed at the R 40 yd. line. Whose ball is it and where?

When R muffed it he effectively ended the series for K. Therefore as I interpret it you would have an illegal forward pass, 5 yards from spot of throw the LOD aspect is ignored because of the change of possesion. since K was the last team in possession it is there's 1st and 10 5yds from spot of foul or if declined result of play. This sounds right but please critique as needed.

(a) first and 10 for K at K's 45 yard line.
(b) first and 10 for K at the 50 yd. line.
(c) first and 10 for K at the R 40 yd. line.

5.1.3.f

K has maintained team possession in all instances.
The pass is legal since it occurred behind the neutral zone.

The muff by R8 invokes 5.1.3.f

See the thread titled "Effect of a touched kick". It is almost identical to your question and has lots of great discussion.

Canadian Ruling
 

After R8's muff, it is fair game. K9's forward pass is illegal - this is an offside pass subject to penalty. In (a), a whistle here would be inadvertant.

Because it was a muff, team possession did not change, so there is no illegal pass. (7-5-2a)