I like!
When you've got syncing overlapping vocals (even when the light's out), I would suggest panning either track to one side, at least a little. I'm not listening in stereo so you might be doing this already, but be careful not to abuse panning though; that's one of the things that's real fun to play with while mastering but can just sound screwy later.
The 'we don't care, don't you care' sounds a bit distorted, not sure if that's what you're going for, but I think that doesn't fit with your soft singing. Distortion doesn't work well with low levels like that, so I'd recommend picking up the volume there if you want distortion.
What Johnny said about the oohs. Scratch tracks, we called them, are also incredibly useful for getting the timing right, so I'd also suggest it in combination with a metronome for that part because the base sounds just a touch loose when it comes in at first, and you want that to be solid. So solid that you'll fell more stable just standing listening to it. Also, I'd try and pump up the bass a bit, at that point it is the star. The bass just comes in and says 'Hey. Get my wallet. It's the one with bad mother fucker on it.' and it just brings in the awesome that is the second half.
When I first listened through on my laptop's speakers, I agreed with Merkava about the bridge, but on better speakers where you get enough of the bass I think it works just fine. Remember to push the bass! Get hard on the picking, get aggressive there and just play it out. That's how I think that should sound there. Your song is rocking then, and the bass is key for that sort of stuff.
I am a bass player and might have some bias there, but you really need it to come in and put an end to soft and put a start on the rock.
But back to the oohs, position the mic above you and tilt your head back so you've got a straight path from your lungs. You should be able to feel it, it'll help your out there, with the volume and tone you need for that sort of thing.
And again, Johnny knows what he's talking about, when you want a strong shout back up and belt it. Just let it go. I'd think it'd sound better centered instead of panned there, but definitely try it out on a side. That's the fun of mixing tracks!
Also, for vocals in general, you might like drinking more citric beverage (grapefruit juice yay!), as it cleans your throat. Avoid sweetened stuff because sugar just coats your throat. Pop is the enemy. I knew a girl who just drank lemon juice. Straight lemon juice. Concentrate. The stuff that comes in the little plastic lemon shaped bottles. That might hinder the soft wavy you've got going in the beginning, but it'll help with the oohs and the 'on fire'.
Composition wise, I'd just say bring in some more drums in the second half (not necessarily from the start), to fill it out more and keep up the momentum. Yeah, totally! When the vocals start, bring in a snare going twice as fast as the kick, and throw in some hi hat semi-regularly, then pick up the pace after the first 'on fire'. I'll try not to get to specific though, you should be able to figure out what you like with a drum machine, but picking up some drums will fill out the last segment nicely.
Once again, rock the bass. It needs a fierce potency there.
I really like the violiny sound that comes in before the bass on the ooh part as well.
Phew. Hope this isn't overkill, but I've had to show a lot of people how to mix and master tracks, and I've gotten super critical 'cause you want a finished product that rocks. Plus I've dealt with a good few kids who don't know anything about recording, but you're definitely doing well here. Most of what I've got to say is fine tuning, I'm just blunt with this stuff because I want it to sound good. But 'sound good' can be subjective, so take what you want, right.