How to find out the folder/file names in the assembly tree using macro?

Sure. You can traverse the feature tree with something like this. Mostly from the top of my head:

Sub PrintFeatureTypes()

dim swApp as SldWorks.SldWorks

dim swModel as ModelDoc2

Dim swFeat as Feature

Set swApp = Application.SldWorks

Set swModel = swApp.ActiveDoc

Set swFeat = swModel.FirstFeature

While Not swFeat Is Nothing

   Debug.Print swFeat.GetTypeName2

   Set swFeat = swFeat.GetNextFeature

Wend

End Sub

You'll see that it will print a 'folder' type and an 'end folder' type. I don't remember the exact phrasing, but it's pretty clear when you see it.

I was working on a similar task a couple weeks ago (sorting components in a folder). The conclusion that I came to was that it is easier to  dissolve (delete) all folders, re-create them, and then insert the components. I found this approach easier to implement because one of the folder insertion methods takes an array of swComponents and arranges in the same order that they appear in that array.

Detect if Assembly Component is in a folder

In my case, the folders were instantiated by a "vendor" property and then some other characteristics like reference models or in-house custom parts. Some of those things were cut out of the attached TreeOrganizer_v04a for public consumption. It isn't well commented but the function names are pretty descriptive so you should get an idea for what to change to get the behavior you want.

When I was working on the TreeOrganizer, I came across the sortPartNumbers macro (also attached). It takes a different approach but appears to be faster than my method and more direct. Unfortunately, I don't know who to credit that macro to. I'm pretty sure I found it on this forum.