There seem to be quite a few posts lately around the media players! I’ve been working through configuring the default skin for audio and made some discoveries that can help with option #2.
I’ve attached my most recent work which has several customizations using CSS to alter various pieces of the audio skin. If you look at the HTML extension, I’ve labeled all the sections and what they do to the audio player – You’re looking for the captions-text, which overrides the setting in the trivantis-player.css using the background value.
I’m not sure how you might be able to add the Spanish CC or how to add the option to the selector (none/English) even after poking around in the player CSS and HTML except for the div class for the selector and radio button for English.
Addendum: I just realized that I uploaded a version prior to saving and re-zipping where the captions background is NOT changed. The section marked as “Changes color for text background” has the * on the wrong side of the / in the note. Sorry about that!