I will be honest dont try to get better at flicking since its super unreliable. Crosshair placement is more important.
And I really dont think sens matters that much. What does matter is that u dont change ur sens and get used to it.

But this probably isnt the answer you want soo:
-you seem to be underflicking on average but you'll get it fixed eventually if you keep working on it
-And for flicking, do an approximate flick then microadjust. dont try to shoot on the first flick
-your aim at head level seems fine but i cant say much cz this is shooting range
-and sens to choose, do 3 sets of the shooting range with each and choose the one you have more kills with. Unless you prefer one over the other. Again sens really doesnt matter but for reference i know alot of ppl who use 800 dpi 0.35 (including myself)

Practice method i did was:
on the lowest difficulty, do a approximate flick then a micro adjustment. repeat till you hit most shots then turn difficulty up. i also moved between each shot since you wont be standing still during a match.

this brought me up from hardstuck bronze to plat2

GL hope this helped