In the hidden room, the Fallen Bishop awaits for you. Just kill him and get Tibia Gold back to where you were. Killing him will let you enter a secret treasure room behind the boss room.
Priest: Low level spirit enchants are the most in-expensive enchants, I've found with my playing style having a lot of spirit on a priest or any caster, cuts down massively on eating/drinking time.
If you have enough spirit you can actually sit down and regain all of your health in 30 seconds. You can start with low level enchants, and work up to things like Mighty Spirit (+21 spirit on weapon)
Warlock: Ah, my personal specialty. Definitely go with "Of the Eagle" first. It is got the intellect you need for mana and the stamina you need... to turn into more mana. Many different opinions here, but "Of Stamina" will benefit you too, as a close second.
Melee: Melee hunters should go for "Of the Tiger" as well (I know some are duplicate) Agility and Stamina is the way to go for the starting out hunter. Hopefully he'll land a crit, and he'll stay alive to crit with the added HP.
Just go pull the levers then the monsters will be popped out and the steel gate is opened. Steel gates are only opened by the levers, but the wooden gates are destroyable.