User Files Download w/o Upload
I would use the organic groups module. The idea is to create a content type lets say "userprivatedir" make this a og group and a allow users to create one or more nodes of this type. By default the creator of a og group is the owner of this group. Then i would create another content type lets say "userfile" and make this a og content. Then you may configure og so only the members of the group (i.e. the user that created it has access into it). The "userfile" content type should have a file field that stores files in the drupal private filesystem (so files are not accessible just by hotlinking but only through their node page.

Also if you dont want user to be able to upload at his own  "userprivatedir" (i.e. og group node) then create the group node by another manager user and then add only this user (or maybe some more that should see this directory's files) to this node group so they have access.