If you have only one podcast, then the settings from the SermonSpeaker options (SermonCast tab) are used and this works fine.
If you have more than one podcast, you need a way to set the different parameters (eg another title). That's where you create a new menuitem of the type "RSS Feed (Podcast)". In that menuitem you then have a tab "SermonCast" where you can set all those parameters again. Only set what is different here, the empty ones will be taken from the global SermonSpeaker settings.
In that menuitem you will also set the filters (eg only sermons from a specific category).
The guid is supposed to be a permalink (url) to the episode. That obviously changes when the item is delivered from a new component (SermonSpeaker instead of PreachIt). It also has to be a non-SEF URL, otherwise the URL may change if you change something in the menu structure. So no, this is not something I can change due to those technical reasons.
You may be able to put up redirect rules, either within Joomla with the redirect component or on server level with apache redirects.
