I'm not sure if it has been suggested yet, or where exactly I should suggest this, but considering the mysterious someone got kicked out recently, could the notification perhaps be changed to "You have received [x] amount of favorites on [y] submission" or something similar? I don't know about other artists but I like seeing if art does well or not.

"You have received [x] amount of favorites on [y]"

"You have received a new favorite on [y]"

"[y] has been favorited [x] amount of times"

Or anything similar to that. This would eliminate the need to address who exactly favorites a submission, thus if someone has set favorites to private there would be no need for "someone". Perhaps if you click the number there could be a little popup list with names, and if someone has favorites set to private it could say "anonymous" or "private favorite"

I think this might be a bit too cluttered, it would need more breathing room, I think

1 & 2) I personally think this is a great idea, yes. Different users have different needs. We are artists, writers, musicians, crafters, fursuit performers and so much more. Some of us just prefer to look at art. Allowing us to customize our userpage is going to reflect who we are, what our focus is on is probably the best solution to the profile page issue. Sounds like a great plan to me. I think modules are the best way to go about this.

As for a suggestion for a module: perhaps something that ties in with the commission system in some way? Could also be useful if that could be tied with the whole journals/updates you mentioned and that way send notifications to user's inbox that an artist is open for commissions. I check this site more often than my email, and with some artists, it's a matter minutes if you make the cut or not.

Another suggestion of mine would be indeed to implement the promote as a module, as others have said. This is for myself and many others a way to discover other art/artists I like.