Building a lantern

I think I might have a go at building a lantern using a couple of 18650s and a driver and a couple of emitters.

I have read another thread where an enterprising person built a floodlight. This is basically what I want to do, but with much less power. I really want to modify a standard 6V camping fluoro, installing a couple of 100 lumen CREEs. What I want is a normal camping lantern that is quite bright (compared to a normal fluoro lantern), but have a long battery life. ie many hours. I am thinking 2 or 4 18650s in a combination of series parallel will give me a lot of capacity. I think 2 100 lumen CREEs - one facing each side of the lantern would give me 360 degree coverage. Since they will be way underdriven, I am hoping that heat will not be such a problem, but I would still mount them on a metal bar. An XM-L T6 driven at less than 500mA will be enough, I think. Perhaps I could get a couple in series and drive them at 200mA, should be even cooler.

This all sounds feasible to me - if anyone can see a flaw in my reasoning, I would love to hear it before I start buying stuff!

Ok - now the hard stuff. I am a bit puzzled by the drivers and was wondering if I can get some pointers. There seem to be a lot of emitters out there. I guess an XM-L T6 is almost standard now, but not necessary.

I think a driver up to 12V, would be better as I can lower the current (so the batteries should last longer).

I have seen some 'constant current' drivers. Are they additional to the base driver - or do they replace the basic driver?

I am thinking I would also have to find a driver that gave the current I wanted. ie something like 1A on high. Since I don't want a lot of light output, is this the way to go? Or should I go for the normal driver (ie 3A), and somehow limit the output mode to 1A? ie how do I get the driver to put out the current I am aiming for? In my case, probably 200-500mA?