Agree on the tail light. The one you picked is sadly dim. You really want the stop light to yell "STOP" in daylight, not just be noticeably on if someone's looking at it. The 1157-x3W-G Flyboy specs is the best all-round brightness choice (it uses the internal reflector): the 1157-xLX3-DI single 3W unit is brighter from the rear but it doesn't give as much light out the sides of the tail light assembly. Although a white license plate lamp is required in some or all stares and provinces, as long as the plate is readable at night it should be OK. In my experience cop cars all have headlights and the cops can read my plate way too easily.
"K&S oblong mini" doesn't specify what bulb type yours use. With amber lenses a white LED loses some brightness, get yellow or amber LEDs if you can. With clear lenses you can use any color you want except red, that's illegal in front and for separate rear turn signals just about everywhere.
White is best for gauges. You can try blue or green but red will be way too dim.
"Idiot lights", use matching colours if you like. Note that different colours look very differently bright for the same lumen output, blue is by far the brightest looking and a brilliant blue light in your face can be annoying. White LEDs have a fairly flat spectrum and can work through coloured lenses and the colours look pretty much evenly bright. Do not do this for the tail light though, you need a red LED!
