Well.. Probably not the greatest phrased questions ever but I'll have a go
1. Both are good at pvp in their own ways - Shaman can do massive burst damage, have decent survivability and are easy and fun to play. I've never played a druid but I know from others that their survivability is amazing, they don't really have much in the way of burst damage, but they rock WSG cos of speedy travel form and utility spells.
2. Neither are really better in PVE... Druids are considered slightly better healers and can tank, shamans are support class, dropping totems healing decently in raids and can off-tank and DD in 5-man/10-man.
3. I THINK Shamans level faster, specced correctly, but having never played druid my experiance is lacking somewhat. I've heard druids level slower but basically never die, whereas shamans CAN kill quickly but you tend to spend alot of time waiting on WF procs
4. I think both are probably quite fun to play, but I will say Shaman as I'm a shaman
5. Again both have their places in instances. Shaman's can Ankh, which is a godsend for when you wipe, and Shamans can res, whereas druids have a half hour combat res but can tank a whole lot better, and are more versatile.
6. Whos good in soloing is basically the same as who levels faster, so see above
Personally in summary - Shaman, but I think you should play whichever sounds like more your kinda thing.