1. If I remember correctly, shooting the blue wires locks the first doors in the corridor you have to fall down to and run through (the one that leads to a dead end but your buddy grabs you from above and then you enter that vehicle and go in the coliseum).
So if you don't shoot the blue wire, when you land on that corridor you are immediatly shot to death, whereas if you shoot it the enemies have to make power shots to break the door (as they will for the following doors).
2. If I remember correctly (once again) that chandelier thing was useful but not mandatory in the amiga version: you could kill the enemy quite easily. But on other versions if he was not killed with it, he would inevitably kill you.