Wouldn't be advising on the completely plain plates, as has been done a couple times now. But more the legal minimum. You still need the posctcode of the place that made them, and the BSA mark (or whatever it is), else it will fail an MOT.
Personally I like the splitter. Its not too intrusive, looks good. I would keep it, at least for the time being until you sort out the rest.
Wheels, I dislike the wheels themselves. For me they are far too popular now, but if your happy, then thats all that matters. Personally, I would only have them a few shades lighter. Not silver, but somewhere in between. BUT, I probably wouldn't bother until they are scuffed to bits anyway, then pay for the refurb / colour change, cos it'll cost the same anyway. Might as well only do it once. Would loosed the coloured rings though. They are rank.
De-badged - YES
Beyond that, I would probably just leave it. An extra 15-20mm lower would make the world of difference, but that all depends on where you live really, if its feasible or not. Or if you perhaps think its "chavvy" to lower a car???