Hi Amigo,
These look very much like mine ?????????
I spent a full afternoon with a wire brush and various other attachments on a drill just removing paint from them, ABSOLUTE NIGHTMARE !!!!!
I tried to keep mine black and silvery but I ended up painting them all black as the alloy would tarnish quickly.
As regards the kerbing I had a similar problem but on the inside of one of the rims and the first time I put a new tyre on it it would not seal.
I took it back to the garage and they removed the tyre and I took the wheel home and set about it.
First I gently knocked the worst of the dink out with a very light hammer and a block of wood.
I then used a alloy metal paste (can't remember it's name) and filled in where the tyre wall meets the wheel and built this up gradually til it was proud and then sanded it back and removed the excess on the outside of the wheel, not necessary as the wheel will be balanced anyway.
I would NOT use a naked heat flame near my alloys other opinions may differ.
Back to the garage, tyre refitted and OK ever since.
Good luck and plenty elbow grease.

A heart broken GLI - R.I.P. A loveable GT. A practical Polo now deceased.