Hardwired Gearset Questions

So I'm just coming back for the first time since TU6 dropped. I've been running OD w/China mask and BTSU gloves but would like to check out HW. I realize they are in the drop pool so collecting all the components to turn in isn't required, but I only have the "M" piece left to find. I know the project lists the missions HW components drop from, but I've got a couple questions. 1) what mission corresponds to the M piece? Or can it be picked up in any mission but I have just been unlucky? 2) Are you supposed to do the missions while invaded or not since I've heard both.

Thanks to all that take time to respond.

JP