I am installing a 3/4" thick hardwood floor. I have two transitions I am concerned about.

The first is the transition to the hearth of the corner fireplace. It seems to be some sort of 1/2" thick flagstone on top of about 3/4" of mortar. Some stones are a little thicker (with less mortar underneath). The stones are relatively flat on the surface.

What would be a reasonable transition here? I've thought about undercutting, but I'm not sure how practical that would be. I've also considered picture framing it with scribed edges.

The second is the transition to the slate tile. The two floors will be very close to the same height. The boards will run perpendicular to the edge of the slate (well, not exactly perpendicular, as the slate tile has an angled edge). This is a high traffic area; I'm concerned a T-mold would get damaged. I'm thinking to try to make a perfectly straight edge with the wood, and fill the gap with sanded caulk.

Thank you.