i hate the chroma set
it's so expensive for something you don't need
i've got this 8$ korean piece of shit keyboard which works great and has a bright backlight
get a good logitech g710+ if you want mech and the g400s mouse combo
your plans for headphones (g430s for a real match, cheap as well) and mic are fine cause nothing else is needed
i'm not too knowledgeable on water cooling but my friend didn't make it look too hard when he built his
you can find a lot of guides about that kinda shit and if it's even needed/useful