Decks, Patios, Porches and Docks - 6x6 Newel posts for porch stair guardrail: surface mount or embed in concrete?

I want to install stair guardrails in the steps of my front porch. I have five steps, so each handrail will be about 6 feet long. I want to install 2 newel posts at the bottom of the steps , top and bottom rails with balusters, which will be attached to existing upper posts on the porch. The steps (and porch floor) are concrete with a flagstone fascia

I want to use 6x6 newel posts (to match the existing posts). Is pressure-treated appropriate? If so, can I surface-mount the newel post, or do I have to embed them in fresh concrete? In theory, the newel posts will be attached to the top/bottom rails and balusters, which themselves will be attached to existing posts -- so it's not completely free-standing. But I don't want the rails to wobble. On the other hand, I heard that embedding PT posts on concrete will eventually lead to rot due to the moisture trapped in the concrete.

If surface-mount is good enough, are there other alternatives to PT? Some cellular PVC or polyurethane?

Finally, if surface-mount, can I drill the concrete/stone fascia with a regular masonry drill and hammer drill? Or do I need to get one of those diamond drillbits and lubricate with water, etc?

Thanks

You can put them in the ground without the concrete. That will save all that drilling & give you stability. The thing with pressure treated is, the price is right but sometimes it's hard to find nice pieces. Cedar & PVC are more expensive but a lot nicer.

I would embed a post or column base in a footing for each of the posts and mount the post in the base. (Don't embed wood in the ground.) You can attach the posts the stair stringers as well if you so desire.

There is no reason to use PT. Since you are matching the upper posts, use the same thing that they are.