Material boarders, height, geometry and shining stars

Hi

I am learning to use Twinmotion and there is a few things I just can’t figure out.

I am using Twinmotion education 2020.1.

The two photos I attached are: A render I am currently working on, and one I previously paid someone to do.

My questions are…

Grass boarders:

On the render I previously paid for the grass i slowly fading out on the boarder of the path. I cannot use the material grass 1 that I am using with the vegetation tool. How do I do this if I want to create this look, and not want to paint or scatter the grass from the vegetation section, as it has a different look than the material grass 1.

Height:

Is it possible to create height/depth in materials in the 2020 version in the same way that it is possible with the height map in the 2021 version?

Geometry:

In my render there is a marble ledge going down a bank (the wider one). In my sketchup file this is just one clean square surface and not two triangular surfaces as shown by the light casted in the render. How does this happen?

Shining stars:

Sometimes these shining stars as shown in the right side of my render appears when export the file. Other times they appear a lot when I start the program then fades away. Other times they stay longer. How to avoid this?

I hope someone can help me with some of these issues. Also I would be thankful for any kind of tips that could help me get my renders up to the level with the render I previously paid for.

Thank you!