more

1) Folder can made not clickable (it only contains sub directories, not a page itself)
2) upload mp3/video files to media dir using file manager
3) More tutorials and detailed explanations. There are many features in modx i can grasp what they do, but descriptions are way too scientific for a non-programmers mind like mine. (freelance designer)

1) Dropmenu already does this (use this snippet to link that item to first child: http://modxcms.com/forums/index.php/topic,1394.msg16794.html#msg16794)
2) you can do that in fckeditor by selecting link and then brows server, or you could set the directory for the filemanager in setting to start in your media dir

hope this helps you,

Dimmy

in addition to explanation of my friend for 2):

You can input as many extensions in System Configuration -> Miscellaneous settings , look for Uploadable filetypes:

And all popular extensions already resides there

regards,

zi