What type of license do I need to use the Microsoft Office Online integration?

Which browsers work with the Microsoft Office Online integration?

When does a file lock in the Microsoft Office Online integration?

Does the Microsoft Office Online integration work with Desktop Applications?

Are Office Online files cached by Microsoft?

What happens if a user is editing in Microsoft Office Online and then another user tries to update in Desktop Sync? 

What happens if a user is on Desktop Sync editing a file and someone uses the Microsoft Office Online integration on the same file?