If you want details on lights etc. the electronics forum is probably a better place. Otherwise, for commuting in the places you describe, I'd suggest something like the L&M Vega or similar. The 200L Dinottes are also not bad, and you can get them in AA style, so you can pick up new batteries fairly cheaply. I suggest the spot beam if you get one, since the wide-beam my be easier to over-ride.

I use older Dinotte's 5W (200 Lumens) flood fixed to handlebars, 3W (120 Lumens) spot on the helmet. The 3W seems brighter to me because of the focus. Anyway, its been a while since I shopped for lights, so I'd head over to the elctronics/lighting forum and do some reading if I were you.