Welcome!
Concerning unit stats: In this regard, the game is neither historically accurate nor consistent in itself. There are quite a lot of vehicles that had the same gun or very similar guns historically, but perform very differently in the game. A few examples:
The Churchill Mk. VII, Cromwell Mk. IV, Valentine Mk. XI and AEC Mk. III all use the OQF 75mm gun.
The M1 57mm AT gun literally is a British 6-pounder.
The SU-76M is a ZiS-3 Field Gun on a T-70 chassis.
The T-34-76/KV-1 both use the F-34/ZiS-5 gun.
The Panzer IV Ausf. F1 and StuG III Ausf. E use the 7,5cm KwK/StuK 37 gun.
The Panzer IV Ausf. H/J and StuG III Ausf. G use the 7,5cm KwK/StuK 40 gun.
The Panther Ausf. G and Jagdpanzer IV/70 both use the 7,5cm KwK/PaK 42 gun.
These are the ones that come to mind right now, but I'm sure there are more. Anyway: To look up stats, I recommend
this website or using the Mod Tools if you want to know something very specific.
As for what you said about the community... well, hours mean nothing. Those could be hours playing against the AI, playing random 4vs4 or running a script to farm warspoils while afk, which was possible in the past. Additionally, the game is probably easy for you to pick up if you're an RTS veteran!