With regards to the weight difference between the 2 espnf1 has Vettel listed as 58kg and Webber at 75kg.
http://en.espnf1.com/f1/motorsport/driver/1247.html
http://en.espnf1.com/f1/motorsport/driver/1214.html
Another article I read recently in the lead up to the singapore gp had Vettel listed as 66kg though.
DC said the weight difference between the two was worth a tenth in F1 Racing magazine earlier in the year.
Marks had some ridiculous ill fortune this year. IIRC he’s had:
Australia – Chassis issue.
Malaysia – KERS faliure on warm up lap.
China – Qualifying mix up.
Spain – Alonso’s magic start then Ferrari pitting on the same lap for both the first two stops.
Monaco – Pit stop stuff up.
Canada – Hamsta.
Belgium – radio mix up for pitting in safety car period.
Suzuka – DRS not working out of spoon on Q3 run.
IMO he’s lost enough points to possibly cost him second in the championship. His poor starts and being unable to max the car in qualifying consistently also cost him many points.
If he finished where he qualifyed he’d have 257 points instead of his current 221, and that’s including 18th for the china stuff up.
Hopefully he’ll get around his tyre issues next year and give Vettel a close run.