The WPK is not the only party in Korea, there’s also Chondoist Chongu Party and Korean Social Democratic Party, you can also be elected a representative without party association.

All elected positions are subject to recall and that right is regularly exercised, being a member of Kim family certainly does not give you immunity to that.

On the more philosophical questions, I can recommend Roland Boer’s Socialism in Power, specifically Chapter 7 talks about Korea.