i run 100% in the dark - 4:15am each morning - my longer runs finish isn the light but obviously - you need to see in the dark - btw - LOVE running in the dark - street to yourself, quiet etc - anyway
1. never used a flashlight - but the headlamp should go on your head and believe me - after awhile you wont even realize its on your head - i have a princeton tec - it cost about fifty bucks but the light angle is adjustable
2. i forget how many lumens (i got the one for 50 at dicks - i just checked the lamp and it doesnt say - it was the brightest they had) and def bright enough - goes thru batts quick so i click it off (easy enough) when in sections lit by streetlights
3. yes - put it on your head
enjoy
edit: i also wear a reflector vest and led blinker - more important than seeing where u are going is other people being able to see where u are going
and dont worry about looking funny with a headlamp on - its early (or late) and no one really cares - btw - try throwing on some camo vibrams and then you'll feel funny:)