Yes, except for some "imported" foreign adjectives that don't have endings and so can't decline, e.g. μωβ "purple, mauve".
What I hear on the audio for "apples" is not "μήλα", but "μήλια". Is this correct? Is this way of reading an exception? Or is this just a problem with the audio?
It actually sounds like μήλλα with a double-consonant pronounciation (that does not exist in Modern Greek). What the speaker does is prolonging the λ. It's an audio problem and not 100% correct.