Rogue- this should help you when raiding

Regarding Mutilate I can't give you any tips or advices since I have never felt the urge to try it out.

Daggers-Priority for stats:
1. Hit
2. Critical Strike
3. Attack Power

Swords-Priority for stats:
1. Hit
2. Attack Power
3. Critical Strike



Rotation
Start with whatever Special Attack you using and use your combo point on a Slice and Dice. Start building up combo points and make sure that Slice and Dice is ALWAYS on. A typical start of your rotation would be like this:

Special Attack >> Slice and Dice >> Special Attack x 2 >> Slice and Dice

Now lets say you have 5 Combo Points and 10 seconds left on your Slice and Dice. You can use the 5 combo points on a rupture or a eviscerate and start building up Slice and Dice again with a 1/2 combo point.

Rupture vs Eviscerate
Rupture vs Eviscerate is a matter of taste. Rupture with Mangle provides a secured amount of damage while with Eviscerate you can be lucky to get a high crit of on your target. I would probably recommend using Rupture until you have a decent amount of attack power & crit, then you can play around with some Eviscerates.

Try to have these on you when raiding
Flask of Relentless Assault
Elixir of Major Agility
Elixir of Major Fortitude
Haste Potions- (extra 26% attack speed for 15 seconds very nice)
Thistle Tea
Warp Burger(s)
Grilled Mudfish(s)
Talbuk Steak(s) (or other stamnia consumables)

Weapon(s)

Dual Mongoose is the way to go. However giving the upcoming patch with Zul'Aman there will be a new enchant introduced to weapons called Executioner which will provides you with a Chance on Hit to ignore 800 armor of your opponents armor.

My tip will be that you go with Executioner in mainhand and Mongoose in the offhand - However I can't be a 100% reliable source before I actually get a chance to try it out myself.

Hope this helps