1. The finish is some sort of washed river gravel finish. It appears that the cement around the pebbles has been eroded. If so, it can be replaced, but I don't know any way to repair it. You can ask locally; there may be someone in your area who's worked out a solution.

Is this your DECK surface, or your POOL surface? I've only ever seen that finish used on decks.

2. It appears you have severe copper stains. The good news? You probably won't get black or mustard algae in those locations. The bad news? It looks like crap and is difficult to remove. Acid washing will remove, but damages your plaster in the process.

PS. If it is deck, check the spaces between the stones. If it's cement, it's hard to repair. If it's epoxy . . . it can kinda, sorta be repaired.