most people use ctrl as far as i know
i use alt because it's more convenient, plus over the years i've always used ctrl as a PTT key on VOiP
i have big hands and i find it easier for my thumb to hit alt than using my palm to hit ctrl
as for qs'ing if you have an issue going to the Q, change the button to something that's not used in-game and more convenient for your hand to hit
and maybe get a mechanical switch keyboard if you're having trouble, that could be your main problem
some people use the 2-1 method to QS instead of QQ
i go back and forth, depending
2-1 method is press to for your pistol, then 1 for your primary, if your keys are setup that way
the way i hold my hands, 2-1 is much easier, but on this suck game, it seems double Q works better IDK
and tap your gun, don't hold left click
lower your sensitivity if you're having trouble controlling recoil
get better hardware if your fps isn't 100+ consistent, or adjust your settings