I got a couple of questions...
1. When you repair a weapon that you found in a random encounter it says it has seen a few repairs, does this do anything statisticaly?
Weapons found in enocunters have already been broken 5-7 times. More time a weapon have been broken, faster it deteriorate.
But all weapons will have this "seen few repair" if you repair it at least one time.
2. Is DT taken off a burst as -x or -x(y) (or for example dt for normal combat leather is -2 or is it -2(the number of rounds shot))?
DT apply on each bullets. Though, bullets with Armor Piercing perk does DT/3.
3. Once all the bases have been purchased, are they perminately gone from the base sellers? (Untill wipe)
I don't understand the question.
4. Do Pkers have realy high perception to always start first in combat?
Some maybe. But if you drop in TB encounter while combat is already active, you will have wait the end of a total turn (from max sequence to lower sequence, you excluded), a new turn begin, and then you will have your turn in normal order.