Need help with 3 player co op campaign achievements

I’m needing the achievements for completing an act 3 players and play as jack in act as well I’m thinking act 4 as it’s the quickest could anyone help please?

I’m not even playing for achievements yet, still wading though the campaign solo. I’ll gladly help in a few weeks when I might be ready to dive back in and do some achievements

That would be great thanks I got no one else to play it with need 1 other I might look for collectables and Jack upgrades I missed a few

Re Jack. How do I pick up heavy weapons and revive. I have both perks