User1095185381 posted
Well the first two are easy and the last one are definitely possible.
1. If you can use .NET 3.5, you can use UserPrincipal from System.DirectoryServices.AccountManagement and if not, you can do it using DirectoryEntry in System.DirectoryServices.
2. using System.IO.Directory.CreateDirectory() - the daft sods at Microsoft decided to call the things you put files in Directories in .NET despite years of referring to them as folders in Windows. So, you get DIrectory and DirectoryInfo (folders)
and DirectoryEntry and DirectorySearcher (ActiveDIrectory). Doh!
3. using P/Invoke: http://msdn.microsoft.com/en-us/library/bb525384(VS.85).aspx E.g. http://www.codeproject.com/KB/dotnet/pinvokeaddshare.aspx
4. t looks like you have to do COM for the fourth with IDiskQuotaUser. (E.g. http://www.codeproject.com/KB/system/DiskQuota.aspx).
5. http://forums.asp.net/p/969995/1400413.aspx