It would be nice if you could login without being redirected from the page you are looking at. For example, to favorite a gigapan right now you have to:

Click “Favorite”
Login (then get redirected to your home page)
Click back to return to the gigapan page
Click refresh to show logged-in options
Now click “Favorite”

The most convenient method would be if you have to log in to do something, that action is automatically completed after you enter your credentials, I think webpages with a Facebook “Like” button do something similar. Just a little quality of life suggestion.

Yes, that gets my vote.

I agree. Best if you can stay on the same page you are viewing immediately after you log in.