1. How do I submit new episodes to my podcast?
You can add new episodes by modifying your RSS feed. You know . . . the file whose public address you submitted to iTunes . . . it likely ends in .xml or .rss. So, you open that file up (probably in iWeb in your case), add a new episode, and put the updated file live on the web. The iTunes crawler will come around later, read your feed, and put the new episode up on your page in the Store. (You cannot modify your feed through the iTunes Store - no matter how hard you try, just to warn you!)
2. How do I remove a podcast from itunes (the entire podcast, not just an episode)?
From the
Tech Spec:
+If you are no longer creating a podcast and you want it removed from iTunes, you should:+
+1. Log into iTunes.+
+2. Find and select your podcast.+
+3. Click on Report a Concern.+
+4. Select "is mine and I want it removed from the Music Store" from the Choose a Reason menu.+
+5. Explain why you want the podcast removed.+
+In most cases, we will remove the podcast from iTunes, especially if we find that the podcast is no longer available at the feed URL.+
+If you want to remove your feed temporarily, you can use the <iTunes:block> tag described in the iTunes RSS Tags section below.+
