Sharp mask pattern transition between landscape layers and "artifact" on landscape

Hi everyone! I’m pretty new to UE4. I’m working on a landscape material at the moment, and I have a few questions.

  1. I want to achieve a masked blend where the transition between the layers has a sharp edge pattern with no soft fade/transparency. I want to have full control over the brush and paint the different layers manually. When the brush has its tool strength set to e.g. “0.5” I want it to paint patches of one material where the patches are still 100% opaque, to build up the layers with a nice and sharp transition (e.g. stones on top of mud). I also want to be able to have multiple layers (more than 6) and also get the effect that I’m looking for. I’m not sure how / what nodes to implement to get the masking effect. how do I get the masking effect?

  2. I also get some sort of “artifact” on the landscape when I sculpt areas with sharp angles (see the picture attached).

The landscape gets hard edges and I am wondering if there is a function/node that can be used in the landscape material to remove this, so I won’t need to smooth all areas on the whole landscape manually? I’ve googled around a lot but can not seem to find an answer that fulfills my requirements. Does anyone have any tips that I can add to my material to solve this? It would be much appreciated! Thank you!