This site is invaluable to the process and it has a lot of good information on Book of Memories.
http://www.silenthillmemories.net/sh_book_of_memories/info_en.htm
Personally I think strength is the most valuable stat. I also think that the durability charm will go a long way, because I spent thousands of MR on tool kits to repair my items. The charms I wouldn't recommend would be Charm 4 and 8.
Classes
The only differences that you have are the starting Artifact Slots and possibly further artifact slot stat bonuses.
Preppy: AGI+; INT+
Goth: VIT+; MND+
Rocker: VIT+; STR+
Jock: STR+; DEX+
Bookworm: INT+; MND+
From the starting stat bonuses to artifacts, you can assume that:
Preppy: Focused on long range combat, Agi supports long range attacks and Int supports wildcards which can at times be short range (see Robbie Doll)
Goth: Focuses on tanking. Vit increases your defense and how much you heal yourself, Mind affects non-direct attacks and also increaes the duration of your Karma abilities, pair that with Light and you basically maintain yourself as a healing tank.
Rocker: Reliable close range combat, think a soldier class or something. Vit increases defense and healing, Str increases your melee attack power.
Jock: Seems to be the close range glass cannon. Dex does increase your blocking capabilities but you need to actively block, it also increases your critical chances. So Jock seems initially aimed towards doing as much melee dam.
Bookworm: Indirect combat much like the Prep but relying on the non-physical it seems. So Wildcard weapons and Karmic abilities.
Mind you though, these are just the bonuses you get from the Artifacts you'll have, they don't set in stone how you'll build your character and for what purpose. You can just take these little bonuses as what they are, just little bonuses as opposed to guidelines as to how to build your character. That and, I have no idea what the other Artifact Slot bonuses will be for any of those classes, at least not yet.
Charms
Left to Right. Top to Bottom
Charm 1 - Lucky Clover: Durability++
Charm 2 - Yen: MR(Memory Residue/Cash)++
Charm 3 - Compass: Map++ (Save Point, Shop and Exit marked from the start)
Charm 4 - Cross: Karma++
Charm 5 - Heart: HP++
Charm 6 - Meatbun: Exp++
Charm 7 - Robbie's Head: Critical++ (Guessing critical chance here)
Charm 8 - Ninja Star: Speed++ (Guessing movement speed)
Tip for extra MR
This is really just common sense after a short play of a few minutes but.
Don't break your weapons. When they become red, just replace them with any other weapon on the battlefield. When the floor is cleared of threats, go through the floor again and pick up all used weapons you dropped. Sell them at the shop, then just make sure you have a fresh weapon before solving the floor's puzzle and going to the next floor.