Okay, so in today's updates, I've added the grenade parts (rare-ish drops from bombers), slightly (very slightly) increased the chances of a taser battery dropping, and added weapon experience sliders to the Terrorists Options menu (along with a handful of "default" settings). I recommend the 1X Default for WADs of 3-10 maps in length, and 4X Default for megawads, but feel free to mess with them.
NOTE, though, that currently the weapon experience bars are broken, so you will presently not be able to tell exactly how much experience you need to level up. I'm considering ways to get around this.