Do you guys think this would be a good idea? I am thinking of playing human, male or female. I am going to adventure with a party that is already set up and we dont need anything else so I can play whatever I want :D . I am thinking about these stats:

St:12
Dex:15
Con:12
Int:8
Wis:13
Cha:12

Do you guys have any suggestions for weapons? skills? feats? spells? Anything at all! :D

Thanks in advance.

[Or should I just go pure monk or pure sorcerer?]

Switch the Dex and Wisdom, a high Wisdom is much more essential to a Monk than Dex. I's also think about lowering the Strength to 10 so you can have a slightly higher Charisma; you should be using your spells, not items or stats, to make you a good tank.
As for items, go after them in this order:
1. Items that increase Wisdom.
2. Items that increase AC.
3. Items that increase Resistances.

I thought once of going a sorcerer 1/monk x. Memorizing shielding spells - mage armor and shield.
And it'd be pretty good too.
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thats how i meant to do it. But you'll probably have a higher level sorcerer so you'll need more charisma.
Also no matter how you look at it your sorcerer spells should be concentrated on improving yourself - buffs. Becouse you can never get a really high score in Charisma your spell DC's will be too low for any save-throw allowable spells. It all depends on what level will your party and you be, as well as what kind of mixture of monk and sorcerer you want to make. Powerplaying wise of course. Roleplaying it'd be cool to cast hold on someone and proceed to smash it into a bloody pulp :D

Weapons: there's really nothing better than monk fists, unless your party will keep finding some really powerful magical kamas ;) (other weapons are all excleded since you cant get as many attacks as with fists and kama's)

Skills: Hide&Move Silently of course. Also if you have SoU Tumble is a must as well. Other skills to your preference.

Feats: I'd take dodge and luck of heroes *shrugs*. Weapon focus:unarmed strike would do just fine as well. At lvl3 take whatever you want. When you reach lvl6 you should have dex of 15 and get circle kick - if you have SoU that is.

BTW, about switching dexterity and wisdom... i wouldnt do that. All wisdom does is increase your AC and raises DC for stunning fist. Dexterity raises AC, increases ranged attack(you'll probably need this) and provides some skill improvments - stealth and tumble.
The difference is minimal though, so you can take whatever you want.