He was kidnapped by his father's servant.
Kate is trying to convince Keller that Annie will be good for Helen.
The russian revolution was indeed a failure
It's been a while since I've read the book and I don't really a lot of the context, so just from this passage I would say it says he notices nice houses and other people's wealth and maybe envies them a little bit. (although you don't get that explicitly from this passage.)
The singer, who was very talented, knew the words to the song.