3” vent pipe through Granite foundation
The core drill is defiantly the way to go. Last time I drilled granite with a core drill it took about twenty minutes. It probably would have taken an hour or better trying to drill it with a hand held drill and that's if you could even get it started.
Their is a bit involved with core drilling, it's pretty simple but their is a learning curve. To mount the core drill on the wall you will need some way of fastening it to the wall. Usually you use a double expansion anchor. Drill a hole with a 3/4 bit then get your anchor set by putting a piece of threaded rod in it, place it in the hole you just drilled, then tighten a washer and nut onto it to expand it and lock it into the foundation. You can then mount the drill on the rod. Remember that the hole you drill will be below the 3/4 hole whatever distance it is from the mounting point on the drill stand to the center of the drill itself.