>In VFP6, cd ? presents the current directory as the 'root'.
>In VFP8, cd ? has some sort of algorithm which will present either the current drive's root directory as 'root' or the 'My Computer' as 'root'

Would CD GETDIR() work for you?

>In VFP6, justStem() on a directory return the right most directory name.
>In VFP8, justStem() on a directory returns an empty string.

The justStem() function doesn't know if the parameter passed is file name, directory or something else so it's not clear what you mean.