There’s an existing feature suggestion addressing #1. I suggest you vote/comment in that thread to avoid duplicates / distraction of votes.
You can already configure Plex to automatically delete shows x days after watching them. Check out the Advanced tab of an individual show (Edit the show entry, Advanced > Delete episodes after playing). From what I remember, this feature focuses on DVR content but you can configure your local tv-shows just the same.
Therefore closing this thread (#1 → duplicate, #2 → implemented)
