i'm -1000 NT. an NT kills me, he drops from +200 to +60. what's with that?

The penalty isn't based on your dynamic score yet, just on your nation.

Well.. i killed Akkiski (-1000 with NT) in s6 and got a little increament with itani. No NT change...

in one day, I had 200 with nt, but by the end of the day, by killing sam II 5 times, I had 15- with nt :(

Yeah, this should be fixed now. Er, sorta. The faction penalties are still weird. Aside from the huge harsh sector-based penalties there are fixed penalties for killing people of other nations, depending on what your respective nations are and how friendly those nations are with one another.