A mixture of epoxy resin thickened with as much Saltillo tile dust as possible, should be the consistency of peanut butter when ready to apply to the surface. Epoxy resin kits are available at marine or large hardware stores.
To age Saltillo tile, you can use a mixture of water and vinegar to create a patina. Apply the solution to the tile and let it sit for a while before rinsing. You can also try using a color-enhancing sealer to give the tiles an aged look.
Saltillo tiles can be used for flooring but are very porous and not recommended for outdoor use or in cold damp climates. They need to be installed and sealed very carefully and looked after well to retain their appearance.
depends on the kind of tile & the thickness & obviously the test method Ceramic or Saltillo will break much easier than Porcelain need more info
Based on my data there is a varying amount of holes in a ceiling tile but the average number is:5162
Porcelain tile is basicaly glass & doesnt need to be sealed, sounds like some sales person is trying to sell you a smoke grinder. The grout should be sealed but your wasting your money sealing a porcelain tile. Ceramic, maybe, saltillo absolutely, but not the porcelain.
DOWN!
A mosaic
If you are asking about tile, no. The joints filled with grout keep the water from getting behind the tile.
None, if they are intact.
The most practical way if holes are larger then 1/2" is to replace the tile. If the space is 1/2" or less sanded grout can be used.
Can it stain something else - no.Can it be stained from something else - yes.
You need a diamond tipped drill bit to drill glass or tile.