I basically have these issues and tried to scour possible solutions for these. I even attempted reinstallation but fixed it temporarily until I was signed back in.
Fullscreen Window mode - I believe you were supposed to be able to move your mouse off-screen for multi-monitor displays when not in battle. This worked temporarily when I finally decided to re-install but the moment my account was signed in, the issue returned. Could this possibly be a setting issue on steam?
Gun sounds too loud - This mostly is an issue with Naval battles since big guns makes big noise. I tried lowering the volume settings but would not change even at lowest setting.
Russian voice lines - despite setting my voice lines to English speaking or by nation (I mostly use US tree), it would mostly be Russian voices even with the simple Thank you.
Would appreciate some help. Tried to report this using in-game “Report an issue” feature but not sure if it would even be read since my report.