My g/f has a silver Leon of the same spec and I love it. It is the only car I have checked with VAGCOM and it consistently shows up no faults other than one time having the temp sensor issue. Every other car I check, including my Cupra TFSi lists atleast 1 or 2 faults, mainly interior monitoring systems.
Anyway, I rarely bother commenting on cars in readers rides unless it is someone I know, but this particular model is one I am familiar with
I see what you are trying to do, and wish you luck, but if it was my car, I would stop your plans fairly soon. The colour coding you have done looks good. You should add front fogs, the suspension and a subtle exhaust upgrade on the back box only probably Cupra style with the twin round exit and not designed to be too loud. Potential performance gains from the 1.6 16v are very minimal and therefore cat backs, remaps etc are really a waste of money.
Not keen on the rear lights as I am an OEM man, and you should really colour code in the reversing sensors. Also, if you can find them and can raise the funds, get some Cupra or Cupra R bumpers on there too
The spoiler you want and some of the other things may be OTT in my opinion, they will cost you dosh, and if not fitted correctly, will make the car look and feel cheap.
I am assuming you are quite young, so hope this post does not come across as condescending