Hello Tim !
I will try to give you more informations :
You can fin my wordpress here : http://podcast.proxi-jeux.fr
My feed seems ok : http://podcast.proxi-jeux.fr/feed/
I updated the podcast's informations weeks (months ?) ago in the "settings for the default feed" part of the plugin. It seems that it don't synchronize anymore after the first time.
I understand that the 2nd and the 3rd issues are linked : as I only generate simples .mp3 files no image is displayed in the cover flow.
I tried few times to generate enhanced file : I use garageband, inserted images and so on ... and uploaded a .m4a file on my FTP server. Once, it was not possible to play it from the WordPress, and the other time, instead of that particulary file, the file displayed in Itunes was a PDF file found in the web site ...
Please, note that I want to be able to display a mp3 / m4a player on the site for non-apple device users, and display the m4a file on Itunes.
Thanks a lot for your help : I Like podpress as it is very simple and powerful, but I spend a loooooooot of time on it, and I would prefere to spend it on my podcasts ;-)