I am having an issue with the version of Unreal Engine 5.4.0

Dear Unreal Engine Forum members,
I am contacting you with the problems that arose during my testing of version 5.4.0. Firstly, I encountered a problem working with landscape. When placing the Landscape custom brush, landmass noticed that in order to see the changes on the map, it must be 100*100 in size. In addition, you constantly have to either click the cap shape checkbox to see the changes, or restart the Unreal Engine.
Secondly, I have a problem with coloring. I loaded all the necessary textures into Quixel Megascans (Bridge), but something goes wrong while coloring landscape. For example, when using the NORDIC FOREST GROUND MOSS COARSE texture and running the game in the editor, the bump on the texture turns out to be 4-6 people in size, and FPS decreases. Attempts to reduce the image quality to 1024p did not solve the problem.
In addition, I have difficulty understanding how meters are measured on the map. For example, I need a 64 km2 map, but I don’t know what parameters landscape should have for this.
These issues are preventing me from continuing to work in Unreal Engine, and I would appreciate any help or constructive advice. I hope for your understanding and support, and I would appreciate any information or recommendations on how to fix these problems. Thank you for your attention and help.