Fringe Winter Finale

Less questions than Lost, but just as mind-blowing.
The premise of the episode is that the bad guys are starting to play with smashing parallel universes, and in particular, the universe as a whole likes to be in balance. So, the bad guys transfer a NYC building, complete with occupants, into our reality. As a horrifying result, many people get glued together because they were occupying the same space in alternate realities. Not quite like what Nina Sharp demonstrated with the smashing snow globes. The worst part of this, according to Walter, is that now the universe is out of balance, and so within 35 hours (where did that # come from?), a building of equal mass in NYC will be transported back to the alternate world. We just don't know which one.
What are the implications for Peter? When Walter kidnapped Peter from the alternate reality, did some other kid get whooshed back as a result? My personal theory on this is that there was different technology in action. I believe that Walter used an earlier technology to get to Alt-Peter - the window that opens up where the 2 realities are close. This is the technology used by David Robert Jones, the technology that Peter and Walter had to close with the little ray-gun thing. This technology doesn't require equal mass transfers. The technology in this episode is not opening a window and moving things through it: it's actually moving things directly from one reality to the other. My alternate theory is that perhaps Walter did a body snatch and left dead-Peter in alt-Peter's bed, but I really don't like that idea.
On to the character development of this episode, which was excellent. Olivia agrees to be a human subject again for the noble cause of discerning which NYC building is about to pop away. She's always subjecting herself to ridiculous risks for the greater good - perhaps because of indoctrination by Bishop & Bell during the drug trials? But this time she gets angry. Confronted with her scared 3 year old self, she becomes infuriated at Bishop. We saw this fury directed at Bell last season, and to a lesser extent, to Bishop. But now it's all over. She is simmering and steaming and Walter finally realizes that this won't help - she has to be scared in able to use her power. But Olivia is never scared - yet another scarring from the early experiments. It's not until she's actually in NYC, facing the prospect of imminent failure and the loss of innocent lives, and the curiously inviting lips of Peter, that she gets scared. Voila, she is able to see the glimmering building and save the day.
But what was she scared of? I think she was scared of love. I have been opposed to a Peter-Olivia romance until this episode. But when they leaned towards each other and Peter moved in for the kiss, I was converted. Let it rock! However, I think the possibility of another romance is what really activated her fear - her fear of miseading the man again, her fear of being in another work relationship, her fear of getting close to anyone (she told John that she's "not good" at romance). Now, Dale disagrees: he thinks she was scared of failure. Maybe so, but I still think that the physical proximity of Peter and the kiss she suddenly realized was coming kicked that fear into high gear.
What do you think?