Hi John
1. Any of the products Dave suggested for grout haze removal (not the Aldon product).
2. The bleach only reacted with the grout haze, it did not eat through the tile. Do not continue sanding the tiles.
3. There are cases that the enhancer will work with porcelain tiles. If you choose to go that route, I strongly suggest you resolve getting the tiles clean first. After the tile & grout is completely dry you can consider doing another TEST area with the enhancer. I have had best success with Aqua Mix Enrich 'n Seal. All excess must be removed and tiles buffed before the enhancer dries on the surface. This holds true if a regular impregnating sealer is used as well.