I'm not exactly fresh, but when it comes to some game mechanics, I feel like a newbie

 

So, what do I gain working for the Dark or Light Side?

 

Is there anything to achieve from being Light/Dark V besides a note in achievements and some restricted items?

 

Sometimes a "Dark/Light meter" is displayed and I get the message "Dark/Light side has won".

I searched on my Dark V agent and my Light V knight, seems there was nothing beside this message.

If your dark/light toggle is set to the side that's won, you get more CXP than if it isn't. There are some bosses that pop around the galaxy corresponding to the side that won, and some stuff for defeating them.

Here's a write-up on Dulfy that explains the whole thing. They've made a couple changes to the system since this write-up was done, like the period of being in a winning state was increased from 1 hour to 18 hours, and you can only see the galactic state on the galaxy map now rather than on the galactic command interface, but it is still pretty accurate.

 

http://dulfy.net/2016/10/20/swtor-galactic-command-dark-vs-light-overview/

Thx for pointing me in that direction. Dulfy's site is always helpful (somehow I managed not to find that page).

 

So- in order to gain DS points for my new Agent faster I should do LS things with the other toons, making Light Side win. Then I get a bonus to all DS points earned.

And unlike the Command Token thing, it does not depend on the level, right ?

Correct, level doesn't matter and if you want to farm alignment points quickly run things that have a high alignment points yield while your chosen side is winning. But, you need to be dark 1 or light 1 to garner the benefit. You can't be neutral.