Is the milky way currently canabalizing any other galaxies? what does this mean, and is there any chance we can be harmed here in earth?
Yes, there is some evidence that the MW is currently cannibalizing two dwarfs: the Sagittarius Dwarf Spheroidal Galaxy and the Canis Major Overdensity. Most of the action is taking place on the other side of the galaxy, so there is little chance it will affect us here, but even if it were happening on this side, there's so many light-years in between stars that it wouldn't affect us anyways.
It has recently 'consumed' at least one galaxy. In our 'local group' of galaxies (about 50 of them), most are small, irregular galaxies - a few hundred thousand to a few million stars in each (compared to the Milky Way's 2 to 3 billion). Our gravity pulls them in, and basically they get absorbed by the Milky Way's bulk, adding their stars to our galaxy. While there is a chance for two stars to get close enough to alter the orbits of any planets, in general stars are so far apart that there's very little effect. So, there *is* a tiny, small chance that something like this could affect Earth, but - at present, and in the foreseeable future - nothing like that is seen on the horizon.
Yes, the Milky Way is cannibalizing at lest 3 galaxies that we know of, maybe more. It mans the Milky Way's gravity and mass are tearing apart the smaller, less massive galaxies. Earth is not in danger.
Even your dust will be gone before there's any risk to Earth.
There is evidence that the Milky Way has already "cannibalized" smaller galaxies. Most of the Milky Way, as well as other galaxies are empty space. A "collision" is really a misnomer. Merger is more like it. There are no catastrophic events, no threats to stars or planets. In fact, mergers may give new life to older galaxies which are replenished with star-forming material. We do not know, but it is possible that the existence of our Solar System may have depended on such a merger- though unlikely, it is possible.
Less of a chance from the assimilation of the Large Megallanic Cloud which is estimated to happen about 2 billion years from now. However, there's an almost certainty of disruption with clouds of gas etc when the huge Andromeda Galaxy and Milky Way collide, pass through each other and gradually coalesce into one super galaxy with their two black holes at the centre merged into one. Because stars are so far apart it is not thought that a very large percentage will collide with each other but, if sentient life is still on Earth 4 or more billion years hence then they will have a spectacular sky at night and probably much increased asteroid and meteor bombardment.