This mod should have no problem working in multiplayer - there are literally no scripting at all. If something breaks, then other mods are doing something funky. I'm guessing modded projectiles don't play well for some reason? Use ones provided by this mod if that's the case.
Weapon ranges are set specifically so each turret type is balanced against each other as well as enemies - I aim for variety, not firepower. Range limits were set up as a tradeoff for firepower of most of the turrets.