You guys may not be aware, but when you buy the bumper, you'll also need to sort out the fog lights, as they wouldn't be included! Just such up on this forum for it, as there are countless threads on it.
In terms of alloys, mine are 17. You are unable to fit any larger realistically.. I have 17" Cupra alloys with the lowest profile tyre I was able to get without it being a terrible ride and stupidly easy to curb the alloys. However, when I bought the alloys (from a Leon) I had to get new tyres as they caused rubbing on the smaller
Ibiza arches. I believe I have 205/45/17 tyres for reference.