The Palantiri

[TarElendil]

My second question is, when Sauron captured the Ithil Stone and twisted it to his use, why didn't the keeper(s) of the master stone do anything? Even Gandalf was afraid to confront Sauron by looking into the stone, would Sauron have been strong enough to retch the master stone away from the control of its keeper(s)? Somehow I doubt it, Aragorn was able to bend the Orthanc Stone to his will because the stone was rightfully his.

i doubt that the keeper(s) of the master stone would even have the power to confront sauron and bend his palantir to their will.
Botht he orthanc and ithil stones were those of the lesser ones compared to arnor or Annuminas. The only reason aragorn succesfully used the stone is because he had a strong enough will to. Him being "entitled" to it has nothing to do with it.