Anything that deals fire damage will drop a cazadore in like, 1 hit. Failing that, shoot their wings off. They're not as much of a threat on the ground.
Ho Ho! Interesting! I've never liked flamers because of the weight, but will incendiary rounds do that, too?
For the OP, you can stay up in the rocks and chip away at them with small guns/laser pistol... it's hard to melee those buggers at low levels. That is good early-game loot, though.