Feed is not working AT ALL

it definitely could be a plugin interfering
disable all of them and see if feed works. if so, activate plugins one by one until you find the offender

if this doesn’t work, try this plugin
http://wordpress.org/extend/plugins/fix-rss-feed/

one error is troubling
“‘utf8’ codec can’t decode bytes in position 43929-43930: invalid data (maybe a high-bit character?)”
help for this error
http://validator.w3.org/feed/docs/error/UnicodeError.html