Two years I to new pool and need some tile advice

[Benkg43]

one of these pics is my fire pit where the stones came off when my cousin’s daughter jumped off the edge. I’m fine using the broken pieces, but what do I use to adhere them?

The other is the spa spillover. I don’t know how bit of an area is impacted, but I’m hoping it’s limited to this corner area. I have zero clue how to attack this. Eternally grateful to any and all advice.

 

[Benkg43]

my installer showed me a picture of this, indicating it wasn't installed under the glass tile which is why this is happening. Put aside the fact that he's the installer, didn't do this, and is saying he didn't do it. The purpose of me adding this piece of info to this post is to give more context and and hopefully spark additional feedback from the smart people on this forum. Again, I am blind as to what to do here. I'm also blind as to whether or not the calcium buildup is a contributor to what I'm seeing, or not. I'm about to spray the tile with one -part water and one-part white vinegar, let it sit for ~15 minutes, and then scrub to see if that takes care of the calcium.

 

[Benkg43]

well, the part water part white vinegar didn't help much in removing the calcium.