1) yes
2) if you want decent runtime out of 3x AA I’d recommend a single mode 350mA AMC7135 driver like this from Kaidomain or something similar. You’ll also need to mount the LED to a piece of aluminium to dissipate the heat.
3) should be ok at low drive current, hopefully others will chime in
4) I would go for something to diffuse the light instead (translucent plastic of some sort) as bare LEDs are very glarey and by diffusing it you’ll make it look “bigger”
5) unlikely, it hasn’t killed me yet and I’m a prime candidate for stuff blowing up in my hands!
Here’s the lantern I modded out of a Coleman 4D lantern, soon to get a Nichia 219 in it (to replace the yucky XP-G cool white):
not quite what you’re after as I only really go car camping and it’d be too big for back packing, but you get the idea 