You can sneak past red lasers using any type of spray weapon. I ain't had the chance to try it on those blue ones yet. You did not know about this, don't even lie because you use crates, destroyed them or used multi tools.
The level designers have spread out a lot of flares in the game, this hints that they're the best utility item and a must have for stealth walkthroughs. I use them a lot and I still have 14 of them as of the MOLE people's hideout.
On your way to the warehouse with the generator, you can stack up a staircase with bins which brings you to the main entrance in less than 5 seconds, making the mission much easier.