i have run in to this several times in the past and it has been difficult every time. leveling the stone is the best option for the mount. it needs to be level because if not it will look terrible from the side. if you are not comfortable doing the chiseling, it is understood, must of us are ot stonemasons. however it is not that hard to do properly, just take your time and be careful.
i use 1/2 inch anchors , usually 4-6" long depending on the stone. you need to make sure that all is level and centered , BEFORE, you drill.
as for the motorized mounts, the omnimount motion52 is awesome. it is as quiet if not quieter than a lutron low voltage shade and is very good about hitting its mark when going to a preset. i was actually able to program a macro that included going to home position and other presets in a ( deep breath) harmony 670. and no i'm not crazy, i said harmony 670 (per customer request i promise).
as for t.v. selection, do your research, that is a delicate balance between glare and picture quality. i'm not gonna get into that discussion.

and as for the responce by cb1: i totally agree!! however ; if you understand your limitations and know how to say "i don't know", then i say go for it. i have personnaly learned a lot in my career by just measuring twice and cutting once, and going for it. remember- it is your reputation (and insurance) on the line!!

Good luck!!