After deleting a file/directory, why cant I replace it with a file/directory of the same name?
The reason you can't upload a new file/folder with the same name as your deleted file/folder is because there is currently a file/folder in existence with that name. "Deleting" a folder or file does not actually remove it from existence, rather it marks it as "deleted", this behavior is in support of the repository's versioning capabilities allowing you to restore files at a later date.
For example the directory Avatar Test was deleted and replaced several times.
To view the deleted directories, press the "View Deleted Files..." button from the menu.
As shown below, the deleted files/directories will appear in red.
How can I set different worlds to have their own individual repositories on the client?
The location of the files for a particular world is determined by a Client Configuration Value called *ClientCachePath*