couple of corrections and additions there.
F&F doesn't mean a unit can fire on the move with no loss of accuracy. Firing on the move will still go by the Stabiliser stat. What F&F means is that the missile won't veer off and do nothing if the enemy unit suddenly disappears.
KE weapons get more powerful the closer they are. I think it's +1AP per 175m?
SA weapons are additionally inferior to F&F because you can only have 1 missile in the air at any time. SACLOS and MCLOS have this too. I have a feeling a few units have multiple control channels, but they're vanishingly rare even if they do.
SEAD missiles have no anti-plane capability, as they have no anti-plane range. They will only fire on ground units and ships.
Infantry fighting on the move is purely based on the stabiliser stat on their weapons. Infantry fighting each other in the same block also use the stabiliser stat on their weapons, and additionally will only fire their MG if it has the CQC trait. No guns aside from infantry MGs have the CQC trait. SMGs are naturally excellent at fighting in block to block combat, as their high rof and good stabilised accuracy is most useful in that situation. Carbines are almost as good, but I have a feeling SMGs have a hidden damage boost or something.
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Israel has a lot of grenades launchers, due to the Merkava IIA transport tank having a Mk19.
Autocannons are KE weapons, and as such gain increased damage up close. it's not uncommon to see a surprise short range autocannon burst obliterate a tank caught with the side or rear showing.
All snipers can hit helicopters. The canadian Recce are notable for being able to slowly plink down light vehicles and have 50% more range than most snipers, rather than slowly plinking down Helis.
Most weapons in the game cause the unit firing them to have highly increased visibility, usually letting the enemy spot them after the initial shot. A few infantry weapons are silenced, however, and this will severely decrease or even eliminate this visibility bloom. Examples are the Vintorez on the soviet Spetsnaz VMF, and the SMG on the chinese Li Jian '90
Honorable mention to the napalm rockets of the soviet Spetsnaz and chinese Li Jian '90. They're some of the finer infantry killing infantry in the game, barely losing out to the US Navy Seals and Polish Formoza due to their grenade launchers.
Edit: Autoloaders on tanks! Some tanks have an autoloader system, which means they don't slow down their firing rate as they become panicked. This isn't signposted anywhere. It's a massive bonus in short range fights, as knife fighting tanks will have a near 100% cth even when panicked. Pretty much the only way of learning which tanks have this is looking them up, but off the top of my head I can say any soviet MBT from the T-64 onwards, the French Leclerc, the US/German MBT-70/Kpz-70 and any of the Japanese ones aside from their cheap meatshield thing have it.