This is something you'd want to speak to the Minister of Magic or Headmaster of your site about. The rules on each site vary a bit per site, so talking to them would be the best way to get an answer :)

Also agreed. It would be a form of transferring galleons between accounts, which people could begin to farm for galleons, causing them to become rich with little work.

This would be a neat addition and very realistic!

This would also be helpful for the library books too, as the only way to remove those comments is the same as the articles: either asking Valentine, or completely deleting and reposting the article/book. 

The library especially gets some interesting and many times offensive or harmful comments, namely on the books about topics revolving around the dark arts. Those can't be removed without the assistance of Valentine unless the book is deleted, which removes all previous comments and likes. 

This would be very helpful indeed! Love this idea!

If you hold down on their name for a moment, then it will pop up. Don't tap the name, as that will take you to their profile!

Bumping this because I love this idea!

If the class is solely about ghouls, ghosts and poltergeists, there will not be enough information to teach a full 7 years of the class. We do not have all of the information as they may have in the class, as we only have what we can learn from Pottermore and from the books/movies.  
Though it is a cannon class in the books, perhaps this could be suggested to incorporated into Care of Magical Creatures?

I'd suggest talking to the Headmaster, Minister, or Library Leader of your site about this! A few sites are working on it, so it may already be in progress!

This is something you should speak to with the MoM and HM of your site. Each site holds different competitions at different times, and some are actually for grads, so the site you're on must not have held one yet!