does it require some kind of endurance or will it drain your action points? is it toggle on off or are you always sprinting and it costs nothing?

You said it, drains action points. Looking forward to that new toy

Drains action point.

There's walk,run,and sprint.

If you played skyrim,it's exactly like that but instead draining stamina.

And rummor is that endurance will set how quickly they drain. Agility as always sets how high your AP is.

See, the only time I can see myself "wasting" action points to sprint is if I know I'm in over my head ---- round the corner and see a Super Behemoth start to grin at me ---- or to dart from cover to cover in as quick a time as possible. In a melee build, I can see it being more useful, except in melee I find VATS a lot more helpful than ranged. In melee, foes are easily getting out of melee range, moving around behind you, etc and it's hard (for me) to target them that close when they're moving around. VATS helps with that, but if I've spent my Action Points sprinting into melee combat, I have little left for VATS (or to run away).

Mixed bag, but I likely won't use it too much. Certainly not for general travel --- that's just asking for trouble.

END determines quick draw? Logically, that's kinda weird, right?

what are you talking about? endurance reduces the amount of AP you spend to sprint (aka you have more endurance you can sprint longer) agility increases your max AP so if you have both high you can sprint much longer.

With that information, it makes more sense. =)

Like Brygard, I think that it'll be much like Skyrim. On the PC you hold the left Alt key down and it makes you sprint and drains Stamina. It'll drain AP in Fallout 4. When you release the Alt key you stop sprinting.