Ah....that mission. Honestly, do it on story once and never go there again unless it's a targeted loot you need.
One of the jammers you can see almost from the entrance where you start that phase. The second is super close(to the right hand side around a corner) and you can rush to right off the bat. The only tricky one is at the bottom of the stairs. If you're really having trouble with it, maybe give some riot foam a try, and run past the enemies.
Hmm....well, you're going to run into a little bit of trouble, since even with a skill build you generally need to be able to land a few headshots now and then. But have you tried the Unlimited Seeker mine build?
https://youtu.be/MkaQw-BNBYA
No, it's a regular rifle drop. I see them all the time. Just farm targeted loot for rifles and you'll get one.
I don't know why people are so obsessed with running Glass Canon in a game that's already known for doing a lot of damage to players. Seems masochistic to me.
Well, there are a few things you can do to make yourself more able to absorb damage.
I really can't stress enough the value of the shield. Even the crusader shield will help you a lot, especially once you get used to moving around with it, and combining it with line of sight and cover. If you're using a skill build, the shield will even be super tough. Check out this one:
https://youtu.be/gmmzlA_Xbzw
Granted, no build in the entire game will save you if you don't have situational awareness and the reactions to move. Enemies are programmed to flank you and drive you out of cover. You have to get good at either constantly falling back, or rotating around the flanks to keep enemies in front of you. If you let them control the situation by staying in one place, you're going to get destroyed. This is just a skill everyone needs to learn about the game, even on the easiest difficulty.
Also of note is that the devs are aware things like Warhounds are too OP, and the aim of things like nade launchers are a bit too punishing. Balance is coming.