audio img size and other support questions

While original audio CD is about 700MB, k3b img file is usually about
743MB. As if some extra data is put into img. I couldn't burn it
successfully on 700MB CD. This was RW CD (I wanted to check if it
writes ok) but would using normal CD 700MB change anything?

By the way, is there any player that can play music from K3b img files
made with cloning option? Can they be converted to other format or is
it possible to extract audio files from these img files?