extruding and scaling without deform?

hello, i dont know how to describwe this so well, im trying to work on a gundam torso right now, and im stuck at a thump trying to figure this out, basically I need to extrude and scale some faces to make a vent, but i cant defrom the faces that im extruding from, everything right now must stay flat, heres a pic of what i mean.

what im asking for is either a method, script, anything that can help me keep shape and still create the faces i need

with the faces selected. scale to the perpendicular axis to 0 ( like if the X axis is running through the topology, scale S axis X amount 0). and this should make the selected faces flat after the extrusion.

Switch to the edge select mode and select the edges you want to straighten and press R for rotate then press X for the axis and then press 0 on your keyboard and it should straighten it out, then you can tweak by hand. Remember to select the horizontal and vertical lines edges! Here are some pictures to let you know what I mean. You have to do this for each and every one of them.

thankyou, i think i understand now