Ah, I agree on this threads OP. Same for me, I noticed my sub had expired once I lost my blue theme. Seeing this thread I was looking around to find how long my subscription works. Finally found it in the VGC-Supporter button (where else, but I started in my profile) to see it is still good til November. Anyways, as I clicked a bit around to find my supporter status.
With that in mind: could you add a button to the profile (like badges and posts) to direct me to the supporter site, as this was the first point I was looking for my current status. Also I didn't see which tier I subscribed too (I know it is silver, but I can't see as I turned off the badges on the avatar). Would be nice to see my current tier there too.
As the person who put the system in place, I think your suggestion are good ones and doable. I'd have to look into it after I'm done with changing the front page hardware chart. Here's my thoughts on each proposition:
I really like your third idea. The button is well visible, but it would probably much less annoying than a notification.