Breach cutter is a carry weapon, if you get the plasma trail on it, you can use it to get rid of lots of swarmers. I always use it when I need to be the most survivable engineer. If you can get the fire OC, that is one of the best allround OCs for it IMO, make it stun, take extra ammo and the quick-broadening mod.

The Shredder grenade can be a life saver - I usually throw one if I have more than 2 and some larger waves appear, especially when swarms of flying enemies appear.

Generally, I turn down the music since the games audio-cues are really important. Before enemies appear you can usually hear burrowing somewhere. The enemies also make characteristic sounds, there are idle sounds and sounds when they aggro or move towards you or your teammates.

What really, really multiplies your kiting ability is to get the Dash perk, every 30s you can dash with it and get away from whatever is after you (and then you can line up e.g. a breach cutter shot to get rid of all the enemies). You can also try to dash through some enemies (though a bit risky on low health), since they take a little time to attack you.

In terms of turrets, get the defender mod and then set them up with the right fire arcs: Many people build their turrets facing away from whatever they want to defend but in the end, the enemies will be where you are anyways. So it’s better to set the turrets up to fire into the space where you’re going to be kiting the enemies (so towards where you’re defending). I usually get the gemini, extra ammo (120 per turret) and defender mod on my turrets.