Some questions about the choice between terrain editor's built in in unity 3D or make all whitin a 3rd partyy program like 3DSMAX.

Hi mates:

I would like to make a question about the choice between terrain editor's built in in unity 3D or make all whitin a 3rd partyy program like 3DSMAX.

a).-What could be more efficient?. a.1).-Using completely the built in system for Unity3D? a.2).-Using the tolls for scatering and painting objetcs in a program like 3DSMAX?

b).-In case of using completely the Unity terrain system: b.1).-How could I change the datil meshes or appearance?: the size, the color of the flowers, the color of the branches of the bushes... b.2).-How could I change the size of the rocks?.

Where are all these settings saved in Unity?. How can I change the mesh of the rock?. And the size of the grass/detail meshes?.

The fact is that some scripts like scatter systems for create ecosystems make random instantiation over a surface (which I think I could implement withour more problem) and this could mean the same cost in terms of computational load for the graphic card or CPU (the idea is instantiate meshes and meshes randomly -or not-) but the problem is: how could I import flowers and grass detail objects' textures from the total and complete mesh generated with my 3DSMAX program?. Could Unity import all the detailed nature scene from my 3DSMAX .fbx file?.