1) you need to reduce the thrust (ctrl) as much as possible for the initial flight or they will continue to advance without your actual ship you can gradually increase thrust (shift) on the flight (be careful though ! ) it is a good idea to use them only after you reached space already. 2) yes, they need fuel, for some reason the dual pylon does not let fuel through, just add some fuel tanks on top of the nacelle (i would suggest the federation ones as the fuel consumption is rather outrageous !) see image: /evilmaddy
