I think being unable to fight the traders is the modder's decision (kind of a neutral faction)
Yep it is basically because there is no way yet to declare peace with the independent faction. In Exerelin the independent faction owns the OmniFactory and the traders, and both these things are important that would cease to function if you were at war with them
Once the mod progresses the independents will have more a presence and can be war-decced, among other things.
Ok, thanks, so no murdering innocent traders anymore :-/
Any Hints then how i still could advance? Waging wars with other factions in my only frigate is no option (And yes i greatly lack of fighting skill here) and the only fleets of rebels i seen had more then 1 Ship
Pick off innocent faction mining fleets, (not too fancy mind you you're just one frigate) You can wait for that good 'ol paycheck and then buy another frigate or maybe even a destroyer. That is all I can think of off the top of my head.
You can also use the mining pod wing in your storage facility to start mining asteroids for supplies, or gas giants for fuel, but attacking another factions mining fleets is usually a good bet
In your Storage Facility there is also a couple of prisoners and agents; trade the prisoners to a faction you want to ally with (or at least not go to war with just yet) and use the agents against a faction you are at/wanting to go to war with.