Actually, i don't know. I only typed what i've read, and i don't really have a clue. Doesn't mean they don't though. With regards to the comet falling apart, this was from an FAQ on the JPL site:

DS: Well comets are pretty fragile. We do see comets fall apart for no apparent reason, pretty well every year - quite a problem with one last year, Comet Linear smashed itself into lots of pieces in interplanetary space. So maybe it was thermal stress as the sun heated it and so on. So we know that comets are pretty fragile. And people, some people, some newspaper reports have cast some sort of worry about this particular comet saying, "Well, if it breaks apart, isn't that dangerous?" The answer is, no. Again, they picked a beautiful target comet. It never comes close to the Earth. It is always at least 50 percent further away from the sun than as the Earth. And as a result, and even if it is smashed into pieces - separate fragments - none of those fragments are going to come close to the Earth. So let's be absolutely clear here. There is no danger to us. This is the sort of mission, which needs to be done in order to work out what comets are made of. There are important, scientific reasons for knowing that. Most of you, most of our bodies are actually made of bits of comets. You know, we're 70 percent water, and that water was delivered to the Earth by comets over the last four billion years. And it will be nice to know what comets are made of, and hence, where the material came from that makes up us - ourselves.

It's pretty clear that they've already considered these possibilities, and even if there was a chance of the comet fragmenting, it has absolutely nothing to do with the probe. As posted below, the probe is tiny!