You can adjust the timer setting in gameplay.constaints, but having pirates attack all players with bounty isn't something that can be modded AFAIK.  That would require a code change (and would probably impact performance pretty heavily).

Is it possible to set up that once pirate raid is launched bounty for that player that gets attacked returns to zero?

Another question

Can timer lenght have up to 10 different values

Let me explain what I mean

First raid is launched 15 min into the game and if bounty can be turned to zero is it possible to set

2nd pirate raid 15 min + 1 sec game time 

3rd pirate raid 15 min + 2 sec game time ........

and  n raid 15 min + n seconds game time where n is number of players in game.

After n is reached next raid would be launched 30 minutes game time when proces repeats itself.