I have a ilvl 90 BLM, so I like to believe I know what I'm talkin' about here.

Fire II is great for mobs of more than 1 (once you're 50 with Flare). Otherwise, you can spam fire 2 I suppose.

Personally, I use fire 2-> flare if running a 50 dungeon. Otherwise, I go single target for 1-2 mobs, and fire 2 to "tenderize" bigger groups. In all reality, it just washes out in lower level dungeons (like Brayflox) so as long as you keep up a rotation of some kind and pew pew, you're good.

Sounds like that other BLM is just an elitist and you shouldn't have been kicked (probably reportable). That said, I don't go for optimal DPS. If they're dying and my mana is flowin one way or the other, then you're doing fine.