1. You can always see when someone has updated via the "mode=full" version of the LJ profile, whether you're entitled to see the entry or not.
2. In the archive/calendar view you can see how many entries were made per day whether you have to access to the entries or not. If you click the number of entries for a day on which no posts are accessible to you, you'll get an error that says there aren't any posts that day, but you already know that's not true.
and that's enough stalking myself, i'll go blind etc.