Syncing in Live + headphone output in live

[Nick <ParadoxQuine@gmail.com>]

Hey everyone,

I've looked in quite a few places and I'm not finding any answers, but
sorry in advance if this is easily found in the live instructions
somewhere.

I'm practicing extracting clips from songs, applying affects, and then
using the clips interspersed into the original songs, so I get
practice with changing up tracks as they play. The only problem I'm
having is that, when I have a full song on loop in one track, and i
have it set to loop, it loops back to the beginning of the song but
all the clips i got from it (during the previous play) are now out of
sync with the song. It looks like, at the bpm the song is and live is
set at, that it should have the beats at exactly the same times it did
on previous plays, but it doesn't, they're all shifted a little. I've
been solving that for clips recorded using my kaoss pad by just
manually telling it where a measure starts, and it syncs its clips
accordingly. How can I do that same thing for ableton live, so it will
either sync beat 1 of the whole song to the samples, or the samples to
the song?

Also, I have a firebox, and I'd like to output certain tracks in
ableton to my speakers via the firebox (currently working great) and
certain tracks only to my headphones. Where should I plug my phones in
(firebox?, comp?, kaoss?) in order to let me select those as an
alternative audio source to my speakers.

Thanks!
Nick