No. They are taking both. Reusable stims are crap now and you have to use single-use ones for min-maxing. Those single-use ones are now tradable. So no advantage except of no cost at farm content.
No, armstech has nothing as far as I know. I unlearned this profession because you have no epic recipes, no bind-on-pickup items, just NOTHING.
You're right, I accidentally grouped Artifice and Armstech together thinking they worked hand-in-hand like Armormech and Synthweaving. But yes. Armstech < Biochem < Artifice < S/A < Cybertech at the moment.