You do not get experience for sneaking past opponents, just defeating them. Playing a survivor does not provide significantly different gameplay from a warrior, except for being a little more challenging. The weapons, stats and skills you choose can make a difference, but the class in and of itself will not provide a significant change.
Sneaking does allow you to get through some areas at a much lower level than you would otherwise be able to do, but by bypassing much of the weaker opponents it will make the strong opponents tougher (since you will be at a lower level). In a game trying for the lowest possible character level finish, Areana played a survivor and did the blessing ceremony at level 12, to end up in the wastelands at level 17 (at which point she quit).
Sneaking can give you a tactical advantage in combat, either by getting the first hit in or being able to make strategic withdrawals.
The experience from quests is higher at higher character levels, but there is no class dependency.
differences between classes (minor spoilers)
Early Starter Tips (NON-Spoiler Version) (contains much of the information in the above topic)
The topic
sorta new, got a quick question contains some information on playing survivors.
