Kylara's covered most everything :]
Basically, TAFL doesn't own the members lists, and we don't have access to anyone's members lists. We can't force website owners to give us the lists, to email their members about no longer being approved, or to remove the TAFL links from their sites if they are no longer approved.
There is no network policy on using member lists from previous FLs. As Kylara said, you can contact (NICELY is best) the previous owner to inquire about using their members lists, but they are not required to assist you or respond to you. Speaking for myself, not as a TAFL staffer, I would not use an old members list unless it was very clear that the FL had been abandoned and was no longer updating - AND I would try to contact the owner first. Some people prefer to email members of abandoned FLs instead of adding them directly. Also, Kylara has posted good suggestions on promoting new FLs to get more members :]
Keeping track of the Updates blog is probably the best way to be notified of removed, moved, and newly added fanlistings. (We have RSS feeds for the Updates blog and the individual categories, too, for those who like using syndicated feeds.) Again, since we don't have access to members lists, we would not have any way of notifying members of the FLs being removed from the network or moved. (And even if we did have the members lists, we would not be able to email thousands of members every day to notify them of removed FLs.)