Webdav for Drupal 7 module development

We require new module with the following features.

Webdav module Drupal 7:

Permissions:
Log in permissions based on Drupal User.
Access permissions for folders based on Organic Groups permissions.
Folders only appear if User has permission
Files only appear if the User has permission

Access:
Able to copy file to webdav and create new drupal node with file as attachment.
If file name is there, add a version number to the file.
Able to control what file type can be written based on file types.
Able to copy from webdav files
Able to delete file in webdav based on folder permissions, node would delete with file.(I don't know if this is a good idea)
Able to create new folders??? I think this might be too tough.

Folder Creation:
Create new root folders in module config

File Volume:
Be able to copy 300 files at one time to Webdav without webdav failing

Folder Query:
Be able to query folder directory 300 times per minute
Folder Query should be quick

Webdav Compatibility:
Webdav should be able to connect from the following client: Linux, Windows7, MS Server 2003, MS Server 2008 R2

File Sizes:
Has to be able to handle file sizes of 50Mb

I am not sure what the file structure should be from saving the files on the Drupal server.
Suggestions.
I would like my files to be stored based on Tokens. private folder/[og_parent]/[og_child/[YYYY]/[MM]/[DD]