Sorry for not answering here for a while, Iron Europe has been and is keeping me busy. Well, i'll still try to answer your questions.
Can you Change the volume of a Sound just by editing the .txt?
That's just a client-side modification, so you can do that with the Module System in a more straightforward way. Refer to the guide by my buddy Willhelm if you want to get the Module System set up!
Is it possible to make the crosshair static, meaning that it doesn't open when I aim?
Yeah, and that's a client side modification as well. Simply raise the accuracy to... let's say, 150 or 180 (make a few tests, then apply the changes to all the items) . I remember i had done something like this for my regiment, but still nobody ever could hit anything
, it's a mere visual change and it wont' affect your "skillz" in any way.
I can't remember if you are able to do this or not; but is it possible to give the 33rd Officer + Ensign a different hat to the rankers? And if so, how would you go about doing it - name in the .brf file, etc?
Ignore those guys above, that's possible too, and you wont get kicked by servers if you do it properly. Obviously, if you do it client-sidely only you and all those who have the modified files will be able to see it, but, still better than nothing. There are lots of mods around which modify hats, plumes, pants, etc,...
So, i'll explain it theoretically. I'm not sure you'll understand it, but this is the way you should do it(i'll assume you want to implement the hat of another unit). Make a copy the hat of the unit you want to implement in BRF. Remember the name of the copied hat or eventually rename it to myawesomehat_copy . Now search for the mesh of the hat you want to replace(a list of the different references can be found in module_items.py from the Module System). Okay, once you found the mesh(you could simply search for the mesh you found in module_items with the "Find in Module" function from OpenBRF) DELETE it, or rename it to myoldhat_copy, but save the name of that mesh somewhere, since we're gonna need that in a while. Well, remember that awesomehat_copy? Rename it to what i told you to save from the previous hat. Save the BRF and you should have your beatiful hats in game without getting kicked.
If you want somebody else to see your beautiful new hat assigned to that unit, just give them the BRFs you modified.