Normally classes with access to domains can pick subdomains, but this is a bit of a special case so I'm a bit unsure.
As for the second part I would say no, but RAW is unclear, if you look at the Icon of Aspects (http://archivesofnethys.com/MagicWondrousDisplay.aspx?FinalName=Icon%20of% 20Aspects) Which mentioned feats and other effects which both familiars and the resistance bonus would most likely fall under, which would mean they are not counted as granted powers, in spite of being under the granted powers section of the domain, like feats.
I would make a ruling that you can use the protection domain ability as if you had the resistance without giving it to you outside of using the ability on yourself.
