Increasing range isn't only meant to hit at longer ranges. It also means that the missile has better kinematics in its effective range.
Not really... the extra booster is to extend flight range, but if it cannot lock at max range then that only works in a chasing engagement with the target moving away from the SAM... which would be ideal for an IR SAM as you would see the engine exhaust of the target, but shooting down approaching targets it usually more valuable than receeding ones.
I seem to remember during the HATO campaign that the Serbs used all sorts of missiles... including R-73s with solid rocket boosters to get them moving from a ground launch... this could be further applications of what they learned... but
for this thread.
BTW a solid rocket booster will improve performance but wont make it cheaper... and I suspect the extra weight means it can only carry four missiles instead of the original 6.
Interesting a laser rangefinder has replaced the radar rangefinder, but they retain the EW boxes either side of the gunners window that detect electronic emissions from the target avoiding the ground with radio altimeters and terrain following radar.
All in all its sensors seem to be passive except for its laser range finder, which will only be used on targets at extreme range to ensure they are in range of the weapon. I wont be horrendously expensive but will be passive so hard for most air forces to spot before it is too late and should have a reasonable chance for a kill... the two stages means it should have good energy attacking the target and the SA-13 missile has a much more substantial HE warhead than MANPADS which is important if the target is armoured or rather big. Would be excellent against ground attack aircraft and attack helicopters and likely would be cheap enough for most major drone types that would otherwise be serious problems for many air defence vehicles.
The passive EW sensors could locate datalinks to make finding drones much easier too...