Green jersey - sprinter
Climbs are rated based on length and steepness Hors categorie (outside category) being the toughest, then 1 through 4, four being the easiest.
ETA - I just found this:
4th Category - the lowest category, climbs of 200-500 feet(70-150m).
3rd Category - climbs of 500-1600 feet(150-500m).
2nd Category - climbs of 1600-2700 ft.(500-800m)
1st Category - climbs of 2700-5000ft(800-1500m)
Hors Category - the hardest, climbs of 5000ft+(1500m+)