Regarding if Soul King is a Deity/God lets look at the definition for
Deity
a god or goddess (in a polytheistic religion).
Soul King is directly stated by Urahara and Ukitake to be a God, his body parts like Mimihagi are also directly stated to be a God and is worshiped like one, he's the leader of the Shinigami which is literally translated from Japanese to English as "God's of Death" and is heavily implied in CFYOW that he's the God of Time as implied by Giriko.
Bleach's Religious foundations are Polytheistic in the Current Cosmology (Mimihagi and Soul King) but where originally Monotheistic in the Previous Cosmology (Prime Soul King)
So he does qualify for this definition.