Here we can see how to use an object list to place some grass. So I have a question now, is there (or how to do it) possibility to make an object list which not only consist of list of objects but some additional information like draw scale for all of these objects too?

not currently, you'd need to create scaled object, and add this scaled object to the list

yup, i've found it how on engine's wiki.
But I have a second question, every time when I try to add few grass objects in to the object list it works but WE doesn't see any meshes and materials that should be connected with these objects from my list.
For example when I add grass0.obj, grass1.obj and grass2.obj to the list I try to put it on heightmap. But engine put into heightmap only spheres without showing an obejcts meshes and materials.
Yes, materials for grass are made exactly like we can see on Esenthel wiki. How to do it right?

are .obj World Editor objects with meshes set (in World Editor - Object Properties)
or .obj - wavefront mesh?