Right now the wall is horrible paneling, I am drywalling the house, but I really want one wall tiled with granite tiles. Would it be better to do this on the paneling or drywall? Will it be too heavy and rip the wall down? Is there a safe way to do this?
Yes you can. However, to simply apply tile to the wall as it is now will not work. You will need to install a cement backer board in place of the drywall. This backer backer board will need to be screwed into the wall studs with 2 1/2 - 3 screws. The seams will need to be taped as similar to drywall. There are many other options available to you other than tile to achieve the look you are wanting. For instance, a plaster compound can be applied to the wall and made to look like a block or stone wall. Stucco or Faux finishes may be a cheaper and easier alternative.
You could put hardybacker up right over the paneling, but personally I would remove the paneling first and then install the hardybacker. The backerboard will not absorb the moisture from the thinset or mastic like drywall and the paneling probably has a finish on it that won't bond very well. Are you meaning slate, as I have never seen anyone do a wall in granite but I suppose it could be done A slate accent wall is very reasonably priced at about 2.00 per foot, easy to do and when sealed with high gloss wet look sealer, can be quite impressive
Yes, you can tile walls with granite tiles. There is a difference in thickness between floor and wall tiles. All you have to do is make certain that the granite tiles you get are made for the wall and not the floor. If you put floor tiles on the wall, they will be too heavy. If you put wall tiles on the floor, they will be too thin to support weight and will crack and break. As for what wall to put them on, it doesn't really matter, as wall tiles will stay up on either wall. As for my personal suggestion, put them on the horrible panel wall. This way, you get rid of the horrible wall and you won't have the extra cost of taking it off and putting on drywall.