ok I figured out the fist thing. I guess just my natural response when going to hit someone is to squeeze the controller pressing the trigger all the way down which arms the guns. For myself I'd make it so that the guns are only deployed if the grip buttons are still held when the trigger is released. So squeeze everything: fist. Hold grip & release trigger: arm guns. Release everything open hand.
Also I ran into a minor bug where I was in the bottom of a U-shaped corridor under some heavy attack. I put my back to the wall and was just firing at the bots coming through both doors. I cleared them out and waited a second to see if any more would come when suddenly an enemy spawned behind my back! It was exciting, but a bit immersion breaking to have it come from nowhere.
Thanks for the help and explanations!