Incorrect validation errors

My feed gets these errors, but they are incorrect

feed: https://drcraigjohnson.org/audio-sermons/?podcast

Additionally, my feed validates with XML. I am using the WordPress Blubrry
podcast plugin and there are many complaints in the blubrry forum about
wrong errors. 
<https://forum.blubrry.com/index.php/topic,6656.msg20125.html#msg20125>  An
alternate validator,  https://podba.se/   was suggested.


This feed does not validate.
* 
* line 27 
<https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fdrcraigjohnson.or
g%2Faudio-sermons%2F%3Fpodcast#l27> , column 1: href must be a full URL:
https://drcraigjohnson.org/wp-content/uploads/2016/03/Dr-Craig-Johnson-Audio
-Podcasts.jpg [help
<https://validator.w3.org/feed/docs/error/InvalidURLAttribute.html> ]
* 
* 
* 
* The URL is complete and works
> * 	<itunes:image href="https://drcraigjohnson.org/wp-content/uploads/2016/03/D
> ...
> *  ^
In addition, interoperability with the widest range of feed readers could be
improved by implementing the following recommendations.
* 
* line 2 
<https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fdrcraigjohnson.or
g%2Faudio-sermons%2F%3Fpodcast#l2> , column 0: Use of unknown namespace:
http://www.rawvoice.com/rawvoiceRssModule/ [help
<https://validator.w3.org/feed/docs/warning/UnknownNamespace.html> ]
> * <rss version="2.0"
* 
* line 2 
<https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fdrcraigjohnson.or
g%2Faudio-sermons%2F%3Fpodcast#l2> , column 0: Use of unknown namespace:
http://www.google.com/schemas/play-podcasts/1.0/play-podcasts.xsd [help
<https://validator.w3.org/feed/docs/warning/UnknownNamespace.html> ]
> * <rss version="2.0"
* 
* line 62 
<https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fdrcraigjohnson.or
g%2Faudio-sermons%2F%3Fpodcast#l62> , column 156: itunes:summary should not
contain HTML: a (43 occurrences) [help
<https://validator.w3.org/feed/docs/warning/ContainsHTML.html> ]
> * ... N-7-SONS.docx">Sermon notes</a><br />]]></itunes:summary>
> *                                              ^
* 
* line 1820 
<https://validator.w3.org/feed/check.cgi?url=https%3A%2F%2Fdrcraigjohnson.or
g%2Faudio-sermons%2F%3Fpodcast#l1820> , column 12: Encode "&" and "<" in
plain text using hexadecimal character references. (2 occurrences) [help
<https://validator.w3.org/feed/docs/warning/CharacterData.html> ]
> * &lt;br /&gt;</itunes:summary>
> * 
> * 
> * Thank you for correcting/updating.
> * 
> * Regards,
> * Michael
> * 
*             ^