literal translation is '재미있게 들려' and '행복하게 들려' but it is very awkward in korean. you'd rather say '재미있어 보여' and '행복해 보여' it may be one of the confusing parts of learning korean for foreigners.

That is 들리다. But we don't use 들리다 like you guys. 완전 감사합니다 sounds childish to me. 정말/대단히/매우 감사합니다 is much better.