There are many users who leave for months and come back to their accounts. Automatically deleting users would delete some that some may not want to be deleted.

You can RP this area in the Grounds RP forum.

This is not a bug and should be posted in the "Ideas" section.

Perhaps there could be an option to turn this off as well in the settings?

Many spells are taught from a theoretical standpoint in Defence Against the Dark Arts if they are dangerous enough. If you want to see one taught this way, you can suggest it to the teacher of this class, but there is no need to make an entirely new class for it.

It's not quite that simple. When you're a teacher, you can select "book" or "wand", and any book or wand will allow the student to take the class. What Thomas is suggesting is that they do the same for parchment, quills, and ink, so that if the teacher would like, the student can then buy any type of these objects and it will suffice. 

The MoM on the site cannot implemented this as it would be new (technically repeated) coding.

They aren't saying that the ATs/teachers need to send owls, they're suggesting a notification for when a AT/teacher does finish filing a complaint. I've had multiple users who have consistently graded incorrectly, but they weren't aware that their grading was being punished because they didn't check their previous grading in the 'your gradings' tab. 

A notification would make them aware that it's happened right away so they can check it sooner and correct the way they're grading. 

You can simply write this into your profile text after grading and use it in RPs. There's no need for it to be added as anything else.

There is no year because the year is Year #. It cannot be a real year, otherwise the year would go spirling into the future and would no longer be modern day. 

The years pass quicker ingame than they do irl, so even setting it back a few years will still not work because soon the ingame year will pass the IRL year.

If you want to know the ingame year, it is simply Year #. It's not the type of year system you may be used to, such as 2018, but it's the ingame year.

You can't assume that all users are active or already know all of the staff members well. What about new users? They join every day, and I know from experience that it takes at least a few weeks to learn who teaches what and who is management for what, and that takes time going back and forth from the job list.

Just because you want to think "Well, if they want to know who teaches what, they should just be more active," because sometimes people are busy, sometimes they need a break, sometimes they are genuinely new to the site. It wouldn't exactly be fair to think that way.