IIRC 3.5 clerics can spontaneously convert their prepared spells to Cure spells. So Durkon (and most clerics) likely didn't prepare most of the healing spells we see, since there's simply no reason to when you could prepare alternate spells and convert on an as-needed basis.
Sure, but Quicken Spell isn't the best possible feat option. Sure, it's fantastic for enhancing action economy, but it's also got a hefty cost with the +4 spell level.