Question 2: When I am tracking a target with "Volkhov", and switch off the transmition, still it calculates point of impact and lamps for beta, epsilon and distanse are green (still I am tracking on AS-AP. I thought that only later SAM's are doing this.

No, even Dvina is capable of it.
The big difference, is that while the Dvina/Volhov is keeping the last good known delta angle, the KRUG is really calculating the predicted target path.

In real life, it was really suggested to switch off illumination for short periods after launch to confuse enemy.
The 25sec lamp of the "A" panel is illuminating to indicate, that you need to switch illumination on.