Hello,

Probably still solve, but can't find

Can a player fire 2 or more différents actions on the same unique trigger?

Example, with Murne 4xps capability, can the player use the "Other heroes" and the "any ally" capability in same time?

Abilities with the same trigger are resolved in the timing resolution order (page 2 of RRG). Outside of attacks the order is mission/core rules, imperial player, rebel players.

If there are more than one ability in each 'class', the respective side decides their order. During campaign the imperial player decides the order of the mission/core rules.

Yes, both abilities on the Waylay card can be used one after another in the order of your choice. (They are separate abilities on the same card with an identical trigger.)

Related, with the rules quotes about simultaneous abilities:

Ability Resolution order during attacks