I am replacing a waterfall in my pool which required me to remove the existing tile at the waterline and I need to replace it. I have a salt water chlorination system. I was hoping I could get some advice for the following questions:

1. Could I use any tile for along the waterline? (porcelain, ceramic, glass, travertine, marble, etc) or should I avoid natural stone? Or are there any other requirements I need to look for?
2. I was thinking of this glass 1x1 tile, but it has metal. Would that be OK? http://www.flooranddecor.com/aruba-m...in-x-1in.html# (if posting links isn't OK, let me know and I'll edit this out)
3. What kind of mortar should I use?
4. Do I need to prepare the concrete surface before tiling over it? Waterproofing?

Thanks!