Video wise, what you are looking for will most likely be in one of the Intro videos here
I'm not really a DGLux guy so I may go wrong here. If I do I'm sure someone will jump in and help out. As I understand it when users are added to Mango they must login to Mango then click the DGLux icon to create the DGLux user. This will create the account but it will still need to be configured.
Q. Also can I make a user type, or a template, with permissions set, so that anyone can just register a user and just pick a type with preset permissions?
A. Yes, assuming you are using a later version of Mango you would configure this on the User's page. After the page loads click the Data point Permission tab. Here you can bulk apply permissions to groups.