I wouldn't personally bother with colour match paint it's just a gimmick really but I've been there and done that, I still have a pot of blue colour match in the garage from my Blue Metro in 1994. Don't get me wrong it's still adequate as a polish but the colour bit really is a bit useless. It should do the trick but you might like to try something with a bit more bite, perhaps T-Cut Metallic to remove oxidation. You could start with clay, follow up using your polish/t-cut and then refine the finish with some Autoglym Super Resin Polish and then some Autoglym Extra Gloss Protection. Quite a bit of effort but the paint should look great and have a decent layer of protection. Get yourself a few micofibre cloths to remove polish/wax with and some foam applicators (I last used a small baby sponge instead). Top up with Extra Gloss Protection every 3 months and hopefully your paint will stay in better condition from there on in.
As for your loss of lacquer the only real way of fixing it is to have the whol bumper sprayed. If you'd like a temporary fix you could try to clean up the area, polish up the underlying paint, make sure it's clean from all grease and silicon then spray lacquer back over the top, will still leave a dip in the paint but might prevent the underlying paint from loosing it's colour.
