Well, here are some of my suggestions, and things that I do to help improve my overall DPS in 5 mans and raids.
1. Get the best enchants you can. Right now, here is what I can see you need on your current gear: Boots + 12 agi, Chest +6 to all stats, Cloak +12 agi, Head - CE glyph if you have the rep, Ranged weapon +12 damage or + 28 crit rating. Your ranged is epic, get the best you can and go above the +10 damage scope.
2. Gems - Gloves - since you are MM spec get the +16 attack power and they are epic, you wont be upgrading for a while unless you get T4 maybe. Essentially get the best you can on things that you are not going to upgrade for a while, such as your bracers. Do not necessarily worry about putting the right color gem in the right socket, do what is best to help your spec out. A hunter needs more damage then life, we have various ways to save ourselves in combat, use them to your advantage.
3. MP5 is nice for hunters, but not necessary. We can get by without tons of it. Yes, it does help out in long drawn out fights, but that is why you have mana pots, and on occasion, you can still FD and drink. Doesn't always work though.
4. Talent build: There are a number of ways you can go about this, I know from talking with you, that you prefer to stay MM. Here is what I would do:
http://www.wowhead.com/?talent=mZVybRVzheotIhzMhc The one point you had in imp arcane shot, won't really help at all. Also, from general experience and consensus the 2 points spent in combat experience isn't all that useful. If you insist on having it, drop 2 points from imp mark and get it. Here is a link to my current build:
http://www.wowhead.com/?talent=VZVtbRVzhxoZIhzMhfMhV This is a hybrid build which does a great amount of damage, but is heavy agility based. And finally, here is the build I plan on going to sometime in the near future:
http://www.wowhead.com/?talent=mZVxbRVZIhzMhfMhVkAo Yes, I lose some upfront damage from losing talents like Barrage and Ranged Weapon Spec, but I gain more AP from having EW up, and with readiness you can dish out a lot of DPS by essentially doing 2 back to back rapid fires. Also, your tanks will love the fact you can do misdirection twice, in a short period of time, giving your raid will be able to go all out that much quicker on a boss.
5. Consumables. This is a huge boost to any hunter. Anymore in a raid, I am using all that I can to go all out and increase my DPS. I use the following items:
Elixir of Major Agility,
Elixir of Major Mageblood,
Warp Burger,
Scroll of Agility V. The Warp Burgers can be replaced with
Ravager Dog or
Grilled Mudfish. The MP5 from the mageblood potion certainly helps out, and makes up for what you would lose in equipment.
6. Shot rotation. Typically, I only use 3 special shots really, and sometimes a sting to increase my DPS. Arcane, Steady, and Multi. Always try and use the arcane and multi since they have the longest cooldowns. When you are firing your shots, I typically use a special, and then let an autoshot fire inbtween the next special shot, that way I do not clip the autoshot. It takes a little while to get used to, but does help out overall.
This all comes down to how you want to play your hunter really. The above are some of the suggestions that I have to help you out, and maybe anyone else needing some help. I am sure that some people may disagree with some of what I said, which is fine. I am by no means an expert on our class, and still have things to learn, but I try and play to the best I can. Remember to watch KTM, and then FD if you have to. If it gets resisted, drop down to more of a steady/auto shot rotation to keep your threat a little lower while the tank builds up more agro, and then go all out and FD again when its up. Best of luck to you, and if you or anyone else has any questions, please message me on here or in game.