Class wise, the least popular is Elf Wizard, followed by Wizard then Monk.
The most popular are Ranger, Cleric and Rogue.
This is based on remaining character cards after the con, and the ones that run out.
Most players at GenCon are casual players, the experienced players usually have their favorities which they specifically gear for.
The spellcaster chart is only available in the training room, so running often helps out. But the spell always works, the spell chart provides bonus damage to the base spell. So memorize a couple each time and you will do fine.
Most runs are normal. Experienced groups will usually organize ahead of time and play at higher difficulty. In practice, Non-Lethal is not very common at all. Most folks want some challenge.
As far as gear and tokens, once you find a class you really like, good Rare tokens can usually be had for 5 dollars or so, which can really help. Any class can go as high as you would like on gear costs.
I am not sure about the value question, I very rarely get anything amazing in the treasure draws, but thats not why I play and volunteer.
I hope this helps!
Wir sind Glücksritter
Wir stürzen die Tyrannen