I myself have been working with Moodle since 2009 here at Uni SA and as such we've made a lot of interesting improvements and enhancements to our Moodle instance.
For various reasons, the code for these is stuck in 1.9 Moodle-land and as such we have a lot of work to do to bring these changes into 2.x.
When the student accesses the Extensions link, they're presented with a list of their current extensions, and they have the ability to request a new extension.
We're using full Moodle Forms functionality for all screens, it should be mentioned, so a lot of these pages will port to 2.x really easily.
Finally, they select a staff member from the drop down.
These staff members are as selected in the Wizard; however again this will need to be configurable in the community version of this module so that it works standalone.
When teachers create an assignment with submissions enabled, students can submit files directly on Schoology.
The recommended workflow to submit assignments will vary based on how students are submitting their work: Students can also submit materials to an assignment using the integrated Google Drive or Microsoft One Drive for Business resource apps, which they can access from the Resources tab.
Our business rules allow students to request a new extension until the due date has been met, whether that's the actual assignment due date, an extension or even a global (group level) extension (to be discussed below).
My intention is to make that functionality modifiable by the institution using the module; as that may not suit everyone.