1, SM. There is no such thing as Msta-SM2.No. Msta-SM2 uses 2A79 gun with 60 cal.
2, 52 cal
3, 2s33 didn't exist beyond a single prototype(scrapped in favor of the much more ambitious 2s35).
Russian armed forces use a mix of old Soviet vanilla 2s19, as well as Russia-produced 2s19m1 and 2s19m2. All of them use 47 cal gun.
Moreover, i frankly doubt at the current stage Russian armed forces really need every brigade battery to shoot at 80 km.
Those who do - division- and army- level fires(given current order or battle, not much difference between those two) - now started to switch to the 2s35.