A more than 2 segments ... tried everything without success
B. vray displacement mod on each segment... tried everything without success
A. It should be no problem at all.
"More segments"- should add benefit of new geometry. Use Randomize node to randomize then.
To Randomize material - no new segments should be added. Use Material node tor randomize material.
B. That is not possible. RailClone uses segments geometry- they You see it in the viewport as building blocks.