Everything appears normal in iTunes in the Store and when subscribing: however I'm not in a position to check on the Podcasts app. Can you give an example of what you are seeing there? (Please identify the episode clearly - the latest would be the easiest to look at).
The itunes:category tag is set as you describe: you would need to change this either in WordPress or in Feedburner's Smartcast settings which I believe over-ride the original feed. I'm afraid I can't advise specifically on either.
This is quite bizzare. I can see where it's getting it from:
<media:content url="http://feedproxy.google.com/~r/StrangeFrequenciesRadioDownloads/~5/a3_x50QZyqE/s fr_show227_full.mp3" medium="image">
<media:content url="http://strangefrequenciesradio.files.wordpress.com/2013/02/dorner.jpg?w=300" medium="image">
<media:content url="http://strangefrequenciesradio.files.wordpress.com/2013/02/writeorwrong.jpg?w=19 9" medium="image">
but why on earth it's reading that tag - which it should be ignoring - I have no idea. All that, and the description tag above it in the feed, are irrelevant to iTunes. If it's possible to remove it then you may get a better result, but I'm afraid that I have no idea what is going on.