Rules for generating starting areas in the new skirmish format:
Question: the generated starting areas may be used by any player? Or each player generates the starting areas that only he/she will be using?

A player may choose any of the placed starting markers to remove and place a figure, it does not matter who originally placed the marker.

I think so too and i hope it's like that, but the rules aren't clear on that point, in my humble opinion, leaving too much space for interpretation

Game Setup clearly shows that the Starting Markers are a shared pool between the two players, because at no point do the rules make any distinction between the markers based upon which player placed them.

I think there's actually a problem with how the starting areas setup is worded.

As written, I read the "rerolling duplicates" phrase as only applying to the rolls made by that individual player. This means that two players could roll matching numbers and there wouldn't be enough starting areas for every figure which is clearly not the intent. Though I can see it being read and interpreted the correct way as well, it is rather ambiguous (in wording, not intent) and could stand to be cleaned up a bit.

Honestly though, it doesn't matter who rolls to determine the location of the starting markers. There just have to be enough rolls to create one for each character on all the starting forces.

Thanks a lot for the answer!

Right. I will be careful and for now interpret It the right way.

Yeah, that bit does need cleaned up. It just needs to say something along the lines of "the player collectively roll 2d10 a number of times equal to the number of starting characters on all forces, rerolling and duplicates".