Can plywood be glued to ceramic tile?

Check with the tile manufacturer or the distributer of the tile, they'll tell you what adhesive to use.

No, plywood alone is not strong enough for ceramic tile. These floors require a very sturdy subfloor at least 1 1/4" thick before the tile. This requires either using cement board or a pored mudbed.

yes If you want them to last then no.Use tilebacker

It is always recommended that you do not go this route, but it is possible. You want to be sure that the old tile is secure and flat. If it is loose and uneven it will cause the new tile to crack or...

I don't think I would, if it is a shiny glazed tile in place now, There wont be a bond between the old and new tiles. If the current tile is a rough slate tile, maybe. Check the recommedations of the...