Vince Vaughn sketch, and some questions

Some basic noob questions which I probably do know the answers to but could do with some clarifying.....
1. Is it better to use more pencils, or less (with varying pressure to product lighter/darker effects with same pencil)?
2. So, after drawing a light outline do you start with the darker areas/pencils first and then work out to the lighter areas?
3. Does quality of pencils and paper make much difference? I'd love to blame the pencils! Ha!
4. Is posture/positioning important? I mainly draw at night, in bed.
5. Have most artists here found drastic improvements over their initial drawings compared to the standards they produce today? ie, will I get MUCH better with practice, or only slightly better???
6. Is hair the hardest thing to draw EVER?!
Think I've waffled enough for now, thanks for reading.