6000 missiles for how many firing trucks ? how many long range radars?

All that's unknown as of now. I doubt most of that information is going to be released anyway. We can only speculate using existing Russian setup.

We are buying 5 regiments, which we can seculate has 10 battalions or 20 batteries at the bare minimum. Some Russian regiments have 3 battalions, but we will ignore that.

We can assume each battery has 4 trucks. And assuming each truck will carry 1 missile type, it can be mixed of course, that would mean each battery has 16 each of the 9M96 family along with 4 each of the 48N6 and 40N6, that will give us 40 ready to fire missiles. Let's also consider there's an equal amount as reload. So that makes 80. So if we have ordered 5 regiments worth, with 4 batteries in each regiment, then we will see 320 missiles in each regiment and 1600 missiles in all 5 regiments. The remaining 4400 are reserves. It's also likely there's at least 2 reloads available in the field, not 1. So it could be 2400 missiles in the field and 3600 in reserve.

Of course, due to the addition of 40N6, it's possible that each battery will have 6 launchers instead of 4. All speculation, but it should be very close to reality.

IAF doesn't use the regimental system though, only squadrons. Which means a battalion consisting of 2 batteries will be an IAF squadron. So the search radars and CPs may have to be reconfigured for such a system. I can't speculate how they will go about that though.