all sounds like a good plan to me! the 18s will definitely fit better. if you wanna upgrade you can pick up some wrx or sti wheels, 15 or 20 mill adapters from 5x100 to 5x114.3 will get em sitting flush. tune is the biggest improvement you can do to these cars...the horsepower gains isn't huge, but the gobs of torque everywhere really liven up the car. BPV, plugs and new coils are good miantenance, same with all the fluids and everything you've done/are doing.
mevotech makes new front control arms with stiffer bushings, worth the change. rear sway bar from an sti (19 or 20 mm) really tightens up the rear end...front is impossible to change unless you raise the engine, and that's...a w hole thing. the perrin shifter stop is a must, makes a huge difference. everyone raves about the clutch damper delete...if you're chaning clutch fluid, that's a good time to do it. i've got the part sitting in my shed, but haven't done it for 6+ years...soon though.
i'll be doing the kyb/OE springs this spring, so i can't comment on that but i've heard it's a huge difference, i'm excited to see that myself. sounds like you've got a good old plan for the car to get it kinda where it should have been from the factory. hope you enjoy it!