@ gunnar123abc...
I usually sell all the human rifles and order Heavy cannon ASAP (use HC-AP rounds), for my snipers (early game they will be doing most of the killing). I keep pistols for scouts as pistol has much quicker snap shot for reaction fire training & also a much quicker aim shot (but you wont be doing much aiming with it, it's mainly for the snap shot).
The difference in damage of the pistol & rifle is 4 points in favour of the latter, but this small deficit in damage is negated by the fact you be having more shots with pistol and better chance of more reaction fire.
For cyberdiscs even HC-AP is relatively useless (but if u try to take them on with standard human rifles then LOL
SUICIDE!!! 
). Instead use Grenadier with HE pack and Heavy gunner with Grenade Launcher with Large HE rockets.
Once you acquire the small launcher use stun bomb for cyberdiscs if you don't want them to explode (however sometimes you want them to explode so this is situational). As said already cyberdiscs cannot be captured- you need to interrogate the alien medic to find more info.
My early squad of 14 usually includes x6 scouts (wielding standard pistols and the usual utility setup I mentioned in my earlier post), 1-2 Grenade Launchers with HE large rockets, x1 Grenadier with HE pack (don't bother with human grenades thy are weak, while alien grenades should become standard issue to all troops as game progresses), the rest of the squad are snipers with HC-AP rounds. Lastly we have X1 Ammo mule (a really strong guy), who carries extra HE large rockets + HE packs.
As game progresses & soldiers acquire great strength the ammo mule is phased out in to the new Grenadier & the old grenadier become sniper as he will probably have most of the kills and thus improve his firing accuracy at greater pace than your snipers- in my current campaign it about 7 month my grenadier went from about 35 FA & now approaching 100.
As game progress I prioritise laser rifles over plasma rifle for scouts (again due to the quick snap shot of the laser rifle over the plasma rifle). Heavy Plasma is ultimate weapon for snipers. So with that said I tend to totally skip over the plasma pistol/rifle.
As for the chryssalids they can be a nightmare. HE packs/HE large rockets work well. HC-AP works too (but not as well), forget about using standard human rifles/pistols. Later x2 shots of Laser Rifle usually does the job.
Chryssalids also have a bad habit of expending their energy so the more prolonged the battle the easier the fight against them becomes as their maximum travel distance is reduces greatly in prolonged battles...
Make sure you use plenty of smoke cover, if the chyss can't see your trooper, chances are very good it wont make a straight up rush at that poor rookie. With that said, once you have flying suits they are almost no threat. And
YES you can capture them, I prefer to do it with stun bomb/small launcher (shoot them with a hit of laser first then use stun bomb- as they can usually take a single stun bomb alone).
I am actually wondering how people will deal with the Chryssalid Spitters in my Mod.
The ranged zombification attack is damn powerful 
Can they spit upwards
