This mod just adds new "admin" items. All existing items are unmodified.

Ok thanks, will the default Unturned guns work too?

Infinite ammo is only present on weapons classed as guns in the mod. Mod doesn't allow you to get infinite ammo on other weapons (I don't think any steam workshop mod can). IDs 65508 and 65509 are classed as guns and won't lose ammo when you shoot them meaning they have infinite ammo. In case you own a server and want unlimited ammo on your guns, plugin ShimmysAdminTools can do that for you.

How do I use Infinite ammo

Wearing full set of clothes of any type will result the same protection against cold, that is sadly not configurable.

do you take cold damage tho