Looking for some advice from some of the great poly modellers here at SM regarding good techniques for adding detail. I've posted this image with a couple of areas marked that need some detail added and was wondering what are the best ways.

For instance, the opening is for the exhaust on the fuselage, i'd always make my cut and take it all the way back the length of the fuselage to the tail, is this necessary? Then there's a close up view of one of the horizontal stabalizers. I can either make cuts from top to bottom and horizontally along the length of the fuselage again or i can cut an edge loop around the base of the stablizer but this always leaves triangles for me. Any suggestions? Thanks.