craftgrrl | How do I glue a postcard to a piece of tile??

Here is what I need to be able to do: I need to take a postcard (or something similar...thick piece of paper with a picture printed on it either that I'm buying from a store already made or that I'm printing myself from my printer at home (whichever will work), matte or glossy paper) and glue it flat to the glossy side of a tile (like just a square one you'd buy at Lowe's) and then put some kind of a sealer over the top of the picture so that the colors will not run if it gets wet. Is this possible?

I recently got a little crafty item at a fair, and it looks like the person took a postcard or maybe printed off a picture on photo paper and glued it to the tile. I'm not sure what they glued it to the tile with because it's very flat to the tile, no bubbling whatsoever, it's on there very well. The problem I've had when doing it myself is that even using a thick paper, it bubbled and I just used a bit of hot glue on the sides.

The item that I got at the craft fair does have one major problem that I would want to remedy if I can duplicate the design. The picture on the paper is starting to come off. I'm not sure what kind of paper it's on, but it's like a rubbery paint is coming off of the paper and that's the picture. Also, when I picked it up and my finger was a little damp with water, it totally smeared the picture! I would definitely want to find a way to seal the picture so that it is waterproof and does not happen. With my first attempt at making this, I tried using a decoupage glue and painting it over the top of the picture, but that ended up smearing the picture I used, so that will obviously not work. Plus it added to the bubbling of the picture which was obviously more wet then.

Also, if gluing the bottom of a piece of tile (which isn't completely flat) to some cardboard (like matchboxes), what would be the best glue to use so that it doesn't come apart? I want to be sure if I'm picking this up by the top piece of tile that the weight of the second piece of tile which is also glued to the cardboard boxes won't be too heavy for the glue to hold. I used hot glue, and I used a decent amount of it, but I don't think it's as indestructible as I want it to be right now...did I just not use enough hot glue or is there something better I could use?

Any ideas or solutions???