This is more or less my second go at being a fanfic author (or whatever you'd like to call it.) I've posted a few of my older stories here, the ones I'm not too embarrassed to admit to (or could actually unearth from somewhere). Some of them have been posted wherever people posted things back in those days, possibly under slightly different names.
And then there's my podfic, which should hopefully all be found here.
As for any kind of fanwork (podfic, translations, art, remixes, or anything else I can't think of) based on anything I've made there's no need to ask permission. Go ahead and do whatever you want. I would really like a link to the result though, just so I can be all excited about it, but if you don't want to share then no pressure. (However I can't speak for anyone else, so if there are collaborations, or something originally made by someone else or anything of the like, you'll have to check with others as apropriate.)