But in a past episode it was revealed that River Song marries The Doctor - it's only alluded to (and a subplot) though - we never saw it. I forgot the name of the episode, but the one in the library with Donna & Dr. The marriage took place in the future for the Dr. and the past for River Song. I won't say more in case you wanna watch the ep on rerun.
But I don't know if the same actress is playing River Song again or another character - her hair color was different, and maybe they just reused a good actress.
About the "Smilers" episode - it was creepy, but, I miss the old writing team.