To answer your Question:
How would I do it? Close to what you have done already. The changes I would make, would be:
Do the card images by collection: Core, Forcemaster vs. Warlord, Conquest of Kumanjaro, etc and Promos (by release (and I would not drop the Promos out as the went in to standard release))
I would then Group: Attack, Creatures, Equipment, Conjurations, Enchantments, and Incantations (Alphabetical Order)
Then further Subgroup: Arcane, Dark, Holy, Mind, Nature, War, Air, Earth, Fire, Water (Alphabetical Order)
The reason I would do the card images by collection is so I do not have to insert images of new stuff amongst the old stuff I have previously done. The index up front would be the piece that integrates the collections into one by Group and Subgroup and then by Level. Would almost love to shove into an Access DB