Don’t think I’ve ever used or cared to check for a Mag2 S&S, but I don’t see why it wouldn’t be possible.
Typhoon has an accessory and material I believe. There may be other restrictions but mat+acc can weigh heavily in rarity and be enough to always give a blue or better (since Typhoon is never green).
Explosive Bastard is beaten by the Atlas Ogre. Torgue generally isn’t any good for tech pools.
For elemental MGs, Atlas (especially Ogre) and S&S (especially Draco) will almost always win out.
Acid & Shock Bastards have a place, definitely… until you get a decent Serpens, then only Shock is worth.