2, Automatic launch will launch No1 missile all the time first.
(if there is no missile at No1 launcher, it will not work)
(If a salvo set, No2 missile will be launched)

it launch missile n°1, if n°1 not present, it will launch n° 3 if present ! right? (and if the "Razreshenie" lamp is already illuminates, and we change to new launcher, with n°1 ready -or n°3 ready- , it will be aunched automatically!) is it right?

Again history is involved.
This system was originally designed with launchers capable of handling two missiles...

“In June 1961 Aleksandr Alekseyevich set about creating a modification that was
designated Neva-M. Our OKB-304 participated in this effort. Our joint activities soon were
crowned with success. The plant assimilated the technology for printed circuit board assembly.
Reliability increased and the military confirmed our conclusion that it was possible to assimilate
the station for series production. This elicited a new requirement: increase the station’s capability
to fire on targets flying at very low altitudes.

Minister of Defence of the Soviet Union

“At approximately the same time, Dmitriy Fedorovich Ustinov proposed that Grushin
place not two, but four missiles on a launcher. Petr Dmitriyevich thought a moment and said:
“’The launcher won’t stand that.’
“Ustinov:
“’Well, humor me. Do it.’

So No1 means channel one.