I don't think you can achieve your goals with Ubuntu, however don't outright accept this answer so that others can respond with additional suggestions/insights.
Here's what I know from your comments and from stuff at my workplace which can't be replaced with Ubuntu and such due to the requirements:
- Wanted: Create users and manage what users exist
- Can be done with Active Directory like services, and they do exist for Ubuntu but I don't know what they are off the top of my head.
- Wanted: Set up their home directories and user space files on an Ubuntu server
- There's probably a way to do this, but the Windows and Linux permission structures are wildly different. To truly achieve this you'd need Linux to work with all Windows' permissions, and they don't match up, so control of filespace permissions is probably not possible. (Storage is, permissions isn't)
- To truly make this section work you need a Windows server with Group Policy Objects for all systems and a Windows file share server that handles Windows permissions.
- Wanted: Control Windows/Microsoft Updates
- Impossible with Ubuntu. What you need here is WSUS - Windows Server Update Services - and that is Windows proprietary and needs a Windows server to make work.
- Additional Prerequisites:
- Windows Group Policy Objects
- Windows Active Directory
- Integration between the two above prerequisites, in order to do user control (what users and groups exist), central management of system policy (so you don't have to manually apply the group policy objects on each system by hand), folder redirection and roaming user profiles (so their desktops come up with all their files, app data is available, etc.)
All in all, what you need is a Windows environment. You are working with Windows workstation computers. You are looking for Windows Active Directory. You are looking for Windows Group Policy management servers tied in with Active Directory. You are seeking WSUS to restrict and control updates such that they can only update from the WSUS server, from where you can approve/reject updates that are available.