If I report and block a stalker on here, can they still see their material on my questions?

There’s no difference whether they stalked and you reported it or if it’s someone that didn’t stalk you. A block is a block. Visibility will also be the same, depending on the visibility you chose for your post.

Yes, when they're logged out, if your post visibility is not limited.

If they are smart

No

F um let um watch