I'm very sure I hear them during the "oooo" part. I'm not sure if it's Mike or two or more guys singing. I heard it now, so don't mind my conscience.
Ugh, now I can't go tell my friends all Linkin Park did was sit in three rooms and put it out, completely raw! XD
Well, benefit of the doubt -- I could be wrong about that. It might just be Shinoda. :* But I'm definitely sure that there are strings that come in after the second verse ...
It's gang vocals by the whole band at the end. They're shown recording them on the DVD (I think on the DVD anyway...definitely in one of the "making of" type of clips either way, might have been one of the LPTV episodes). Nope, no strings. The instrument that comes in during the second chorus is a harmonium. As to how "live" the track was recorded, they tracked the piano, guitar, and Chester's vocals live, then they went back and did the gang vocals, and I'm assuming Mike also overdubbed the harmonium afterwards.
I noticed the harmonium first time around. It adds a tinge of atmosphere to the song without drowning out the main three layers.
Good job anyway. Atleast the main instruments were tracked live. The harmonium sounds nice. It's very popular here in my country..I guess it originated from here as well