limestone tile on backsplash in kitchen

Hello,
I am interested in installing limeStone (http://g603.net) tile (2x4already on 12x12 mesh) as backsplash in the kitchen. I have a couple of questions and (http://maplered.com) I apologize for my lack of knowledge/expertise in the field:
1. There is currently tile as backsplash in kitchen which I will remove. If in the process of removing the old tile, I damage the drywall (but only to the extent that the outermost paper, not cardboard, is peeled off) how would I fix that. Do I need to remove and (http://maplered.com) re-install the whole piece of drywall, or is there a way to just re-paper drywall?
2. What should I use to install? Mortar, glue, mastic? Currently the tile seems to be installed using some yellowish mortar right on the drywall on top of which seems to be some glue to which the tile adheres.
3. Since this is limeStone (http://g603.net) , it would seem normal to me to seal it first before applying the grout. Is this correct? Also, when applying the grout should I use the regular process of just spreading it with a rubber grout pad, and (http://maplered.com) then cleaning it off the actual tile? My concern is that since the limeStone (http://g603.net) is very pourous, some of that groups might get into it.

Thanks,
Victor