The first ways of his father David - The Septuagint and several Hebrew manuscripts omit “David,” which has probably crept in from the margin, for David’s “first ways” are nowhere else contrasted with his later ways. The real meaning of the writer is, that Jehoshaphat followed the example set by his father Asa in his earlier years 2 Chronicles 14:1-15; 2 Chronicles 15.
Baalim - On the plural form, see 1 Kings 18:18 note.