OneDrive backups are limited to the last 30 days for undeleted files, and anywhere from 3 days to 30 days for deleted files. If you believe you have changes in your OneDrive content you would like to undo or revert, you must do so within this 30 day window (or sooner for deleted files). More information on restoring OneDrive content is available here.
OneDrive currently offers 1TB of storage space to LETU students, faculty and staff. Use of this space may require up to an equal amount of space on your local drive depending on how you setup your sync options.
Microsoft has documented the following restrictions/limitations on File Names and File Types in the OneDrive for Business Client: https://support.microsoft.com/en-us/kb/3125202