More newbie Qs

I wish you all a very cheery 2005. You really are a nice set of guys
here (those branding me a terrorist notwithstanding), mostly patient
even at clarifying elementary stuff

Some more Qs, if you don't mind.

1. How does a pilot get to know the distance to the airport that he has
to land in, so that he plans his descent accordingly, in planes that
don't have an onboard computer? Maps I know would give the distance
between two fixed points, but how does he keep track of distance
covered in flight and that sort of thing? To inquire ground stations
such info would be embarrassing, I guess

2. What exactly is a VOR? Sounds like it's a constant all-direction
radio transmission from a fixed point on the airport to help locate
where the airstrip is. If so, does it necessarily have to be from *a*
standard designated point in the airfield, right across all airfields
on earth?

3. If a pilot needs to land at an airport that doesn't have a control
tower, how does he figure its elevation so that he may plan his
descent?

4. When a pilot says, "Give me a vector", what does he actually mean?

5. When pilots use miles in conversations, does it mean the miles we
normally use, or is it always nautical miles?

6. The difference between airspeed and groundspeed is that airspeed is
the net of the plane's speed and opposing windspeed, while groundspeed
is just the plane's speed. Right?

7. What is "density altitude", and how to compute it? If I'm not wrong,
its use is to plan the length of takeoff roll and angle of climb.
Cheers,

Ramapriya