Hi.
I am not sure if I did understand everything in your post, but you are from germany, so ...
i could only research one new armor for my soldiers. I get serveral medium armor plates from the alliens but i can´t research a new one for my solders. I get several new ships..the best one seems the stingray but here too no new rocketlauncher and only two beams from the alliens ufo´s. Here laser and particle.
The Power armor and the AM-missiles are not yet in the game.
I fight only with 5 soldiers. 80 Mission they have and i get several live alliens.
It took me ~200 missions to get to the end of the techtree.
I want to capture an alien base but i can´t get it
You can not 'capture' an alien base. Playing and winning an alien base mission is the current ending of the campaign.
Do you have any tipps for me or a good tec tree? I search for tectrees but they are not complete i think or the are too great...or i´m silly :-)
If you attach a savegame, I will take a look.