Players should be judged against their own era. Think of it in terms of dominance. I find it hard to see what splits Thurston, Lockyer, Fittler, Daley, or Sterlo - but likely only one of them will be made an Immortal and it will probably be the most recent.
I guess so.
I don't really know how Immortals are "judged" as of the current ones, I only saw Johns and Lewis play, and Lewis only at the end of his career in the ARL.
If we think of Immortals as being the best two or three players of the 10 or so years around when they played, all the names you mentioned could be Immortals, as could Thurston, Smith, and Slater (hence people say there are 3 or 4 (Cronk? surely not, GI? not really) future Immortals in the Queensland side).
If we think they should be a standout that is much better than those around them, I think Johns earns his spot, but Lewis doesn't, and based on that, I'd only have Cameron Smith as a current player who could be an Immortal.
But Gasnier, Raper and Langlands all largely overlapped in careers (yes, in one incredibly dominant side) so if they were all included as the best of their era, then there is no reason you couldn't include several current Queenslanders as being great and from an incredibly dominant representative side.
But then you'd have to consider a whole heap of players from the underrepresented 70's and 80's as well.