Firstly, should i use 2x MSAA or FXAA in the game launcher Options(not catalyst). Honestly i cant tell the difference but FXAA seemed to be FPS friendly. Is it even worth it to use AA? If possible, can someone upload a screenshot comparing no AA and 2xMSAA/4xMSAA etc, because i dont know where to look for the differences.

Secondly, since my GPU is 6570m GDDR5, should i update my 12.1 drivers to 12.3? I heard some people say that several cards suffer and other cards benefit from the update.

You can look at http://www.geforce.com/Optimize/Guides/the-elder-scrolls-v-skyrim-tweak-guide?sf2686171=1/#9 and http://www.geforce.com/Optimize/Guides/the-elder-scrolls-v-skyrim-tweak-guide?sf2686171=1/#4 to see SS comparisons.

For me...

FXAA --> On
AA --> 2x

...In the game launcher (I never mess with CCC) works very well. Best relation eyecandy and FPS friendly (For me, I repeat), but I have HD 5850...

You have troubles with 12.1? If not, stick with that for now. Look for more feedback about 12.3 in the next days and decide after. However you decide to do, don't install 12.2 (but I think you already know that).

Personally, I still use the FXAA injector since it allows me to tweak the pre-sharpening algorithms and to add some gamma correction which the game needs when being played on my plasma tv. I also role with the Preset 1 since I like the colors in it, but the majority of its benefit come from altering the gamma of the game's output (without having to mess with it at the driver level and affect my entire display). I do this since I play games on my Plasma where the gamma correction is different than when I'm using my computer on my monitor for actual work. Therefore, I want the gamma to affect only this game and this seems a convenient way to do it.

Ya you can leave them both on Mc....FXAA shouldn't affect performance at all in Skyrim.
I am not at my rig atm so can't link some SS basically best place to find jaggies is Whiterun roof runners and the latticework. I would do some testing in that spot.

As for drivers I saw zero increase on my 6 series card from 12.1 to 12.3 and thus I think they are mostly to support the new 7 series cards. This by no means they abandoned updates for older series but their main focus atm is to support the new and expensive flagship stuff. I would stick with 12.1 at least until we see what 12.4 has to offer.