Oro's age has nothing to do with Yamato having the ability of the 1st. Orochimaru left the village before Yondy died. He did his experiments before he left the village that only Yamato survived. Yamato is about as old as Kakashi. Kakashi was old enough to fight before Yondy became Hokage. That means Yamato would have been alive though young. And he would have still had the same powers. Oro being 50 has nothing to do with Yamato being alive when Kyuubi attacked.
It never shows. Since the only demon he's been around is Naruto and that's sealed for the most part. He has the bloodline move, and he's got the ability to supress Kyuubi. Both he got from the dna of the 1st. It's not much to consider he wouldn't get all the abilities. Maybe not as strong since he's weaker but still.
That's what I just said. Yamato and the 1st both did what they did because of that crystal. Yamato's not as strong as Shodaime but he can do the same exact thing. Yamato even says the crystal is how Shodaime controlled the demons and that it only reacted to his chakra. It reacts to Yamato so he should be able to control demons also. But that's really kind of pointless when there is none to control.