Now see, I haven't been too interested in most of your concepts for guns so far, but THIS! This is actually rather unique and interesting! This is what I want to see in a new gun! Something that actually stands out in what it does! Heat-seeking missiles, huh? The seeking area should probably be little smaller, so you at least have to aim a little. Overall though, I LOVE this concept!
EDIT: Reload speed might need to be toned down a bit too, as this IS a weapon that's a bit tricky to deal with, even if you can shoot it down or counter with flares. Noobs would die in droves XD
I assume, as this deals fire damage, it would have a chance to ignite fires?
EDIT2: Okay, so I'm going to probably end up theory-crafting this gun to death now in an attempt to see how balanced it is, to break down ways it could work that might be interesting but still balanced, and just generally doing crazy shit with it XD I shall post it all in a new post when I finish "testing" it and thinking up ideas, as I'm sure this post will be locked by then. Though I'll probably go to bed first so I can do it after I've woken up with a fresh mind.