If you win a battle and become a level 1 player so to speak then you get an SU (supply unit). this can be spent on building higher (for instance) RObotic building. Lets say it would take you 422 production units to go to the next level. If you had a SU or supply unit you could spend that 1 SU on an upgrade to the robotic building in one shot, and all you have to do is win a battle.
For instance. If you see a planet with a starbase of level 2. It would only take 3-5 destroyers to defeat it. You win. You have to guess as to if there are any other ships to defeat.
Don't know about the artifacts yet but scince I won the last battle I am level 8 and I see many more artifacts that can be purchased now in the trade screen. I think if you were to sell your SU then you get money for them and then in turn purchase an artifact that will give you 10%, 20%..etc toward production points, culture, something like that. Then I think you can sell the artifact later on. Not sure.
I still don't know what or how to do a trade agreement, but I think there is a fee of either 10,000 dollars or 10 dollars, they seem to have commas were the decimal point belongs but I'll bet its 10,000 clams.
Thomas