Wow looks great!!! I found a great tile site, I used to go to estate sales too but now I do most of my ordering online from Glasstiledecor.com - they are so cheap they have great brands, great prices and free shipping - hope this site works out as well for y'all as it does me - bc i am a mosaic nut! Here is a link that might be useful: glasstiledecor

Over floor, yes (sometimes), but not over the walls. This requires removal of the existing walls, then new wall material, cement backer board, etc. then tile - a full job. And be sure to pick a pro. I got a call to look at a 4 yr old (new) shower that was part of a new addition. They said a couple tiles (wall mosaic) were a bit loose, and it was leaking into the basement. When I removed the tile, silicone patch and scratched out the grout, I could see the corner wall studs an inch wide! Not a good install, but shows what some guys will do to save time and materials.

@Millworkman Thanks. That thought about adding another layer (and maybe getting less heat) did cross my mind. I'm not too concerned about it though as we cook a lot and are generally hot natured people (we keep our heat pretty low in the winter). Plus the kitchen is fairly small (less than 200 square feet and that includes a broom closet and small walk in pantry). I'm sure the proper way to do it would be to rip it all out but I worry about damaging the heating system. Is a little heat better than the risk of no heat? Ha!

depends on the size of the tile. That tile in your picture is from AnnSacks (see link above) Chrysalis is a collection of hand cut and fitted artisan glass mosaics that stand out for their beauty and craftsmanship. .Mosaics are film face mounted. .Sheeted repeat sections will fit together in an interlocking system. It says it's film-faced. (which means it comes on a sheet_) But other tiles can come as individuals. this is a 4x4 some come on mesh sheets, some come w/the film on the front. (if the tile is somewhat see-through, like a glass, the film face is a better option since the mesh won't be visible. ) Floor and Decor has this glass tile, much cheaper than the ann sacks. https://www.flooranddecor.com/glass-decoratives/marina-del-ray-arabesque-glass-mosaic-100463090.html https://www.decorsmosaic.com/products/azure-glass-mosaic-tile-in-fish-scale-for-floor-and-wall-cgt012-99