The only ability he has shown to use was Susano'o. Itachi also used Susano'o when blind. Sasuke Rinnegan has tomoe and has shown the ability to use Amaterasu, thus likely the other MS Jutsu as well, not that he has any more coming from that eye. Anyway, when an MS is unlocked the Uchiha's brain, or chakra there changes, Nagato had no such think, but he changed when he was injected by "Madara's Will" (chakra recievers). So Nagato -as far as we know- didn't have any Uchiha blood thus "brain chakra", he also was not the original owner of the eyes, so couldn't use them to their full potential, or seemingly pull Susano'o out of nothing. (I'm pretty sure Susano'o has to do with brain chakra.) Sorry if it's confusing, I hope it answers your questions.
Not really if they sage gifted it like he stated last chapter -giving both power didn't work either- , but he has to have a Rinnegan to be on par with Naruto. Hashirama's DNA also wouldn't have Ashura's chakra; it moves on when the person dies.