i don't know much about devils merc. i got in on a random with him, and he asked if we were taking apps i forwarded him to the site, the rest is up to saedo and what not

So looks like Saedo got most of the tech questions out there, I still got some questions for you here we go. 

I see that you say you have played WoW for 5 years now, I assume not the whole time on a rogue (I hope). Also having been playing for 5 years I would expect you have raided more then just ICC (I hope), not that it's a must but that seems to be all you have mentioned. For someone who has played for so long I am noticing a lot of beginner mistakes most of which Saedo mentioned below.

I also noticed a few times throughout your app you seem more worried about getting new shiny epics then taking the time to learn more about what a goes into playing a rogue. Just remember gear < skill.

You say you think that mods are extremely important yet I see you missing most of the important mods such as Grid, some kind of combo point tracker and Omen. All of these would be important in being a serious raider. If I were you I would take a look at barteder, omen,rogue power bars (cd tracker) or power auras etc. Also I don't see many key bindings meaning you click a lot I assume, key bindings = win ask any serious raider.

If you get a chance to get into a raid post some logs so we can see how you perform in a raid.

These are a few questions I see when looking over your app.

Oh where to start..........

1) Spec:

Not only it is wrong, but I'll get to that in a bit, but your reasoning for how you do your fillers is flawed.    I know this is just filler, but you chose Imp Kick due to the silence due to the increased need for interrupts.   This is flawed because:

1. Bosses usually can't be silenced
2. Mobs generally don't have 2 schools of magic that they switch over to once you kick one.

That is, kick already does a 4 second lockdown on the school of magic it casts.   Mobs generally are silenced for that period, and don't have a 2nd school of magic they start spamming for that 1.5 second of total silence to be of any use.

Unless you're doing this for pvp reasons.    If so, all the more power.   Just saying you sounded like how awesome imp kick is in pve.

Now that's out of the way, let's get to how wrong the spec is.

1. You didn't pick up Revealing Strike.    Why?    Well, it's only really 100 dps drop if you don't use it, but shouldn't every rogue try?
2. You seemed to have gone down the assassination tree too much.   Relentless Strikes is what you wanted, especially since you touted how much energy regen you wanted. 
3. The only Prime Glyph that's correct is Sinister Strike.   You should use Adrenaline Rush with it.    Followed by the choices of Slice and Dice (slightly best), Rupture, or Revealing Strike.

So, the spec winds up more like this:  http://www.wowhead.com/talent#fMGZfGccocbRGo0h:ok0rzocm0

2)   Reforging:   Do you know it exists?   Visit an enchanting trainer, talk to that tall Night Elf mage guy that's standing beside him.

3)  Gems and Enchants:

Mastery, wrong.   Haste, wrong.     The belt seems correctly gemmed.    Agility is your best stat by and far.   That's the only thing you should consider gemming.    Pure agility or some agility varient.      That is Red = Delicate, Yellow = Deft (agi/haste), Blue = Glinting (agi/hit).      And that's if the socket bonus is worth it, likely agi bonuses only.

There are 7 unenchanted items.

Wow, no helm enchant from Cata or Wrath, or shoulder enchant in Wrath, went through all that ICC content like that huh....

4) Gear:

Your offhand is wrong, way wrong.  You're using a slow speed enh shaman / fury warrior weapon.    You want speed, speed for energy regen, speed for that energy regen you said you loved so much.

5)  Resources:

So, how have you been rogue'ing all this time?   Making it up as you go along?    Here's a resource you should start looking up.

http://elitistjerks.com/f78/t111329-combat_guide_cata/

Read it up and down and make your fixes.   Those forums will have info on other specs too if you want to look around.