For any tek, is it absolutely necessary to use a gas mask? Its suggested in at least one (Volvin's.) Would a dust mask be fine? I'm not even sure exactly what I should be trying to avoid inhaling.

SWIM would imagine for MHRB dust. Coffee grinders emit a lot of dust, but the way SWIM uses a blender emits no dust.

You can buy powdered MHRB, so avoiding that step if you wanted to. There are a few chems in the process that are best kept away from you if poss! SWIM found a dust mask and a well vented room to be OK though.

I used a dust mask last and it still seemed to let in some of the fumes, but was okay ish enough- better then nothing.
You def want to use something to prevent your lungs from being seeped in chems though whether it be dust mask or gas mask etc.

I think it depends on the chemicals you are using. I find a dust mask does the trick when using naphtha as a solvent. If you are using xylene it might be a different story.

Just hold your breath.

Pokey