Farming dragons for those last recipes is pain. Piece of advice - health regen pots make you life here really easy. You can be pretty much invincible with Blue Dragon with set of Baked Carp, doing 3 runs on one pack of food.
This game might being in the running for "Longest to Get Quests" category. Good thing it's kind of fun compared to others in the same category. (But even fun games can wear thin after a while ....)
For those of you having troubles with the grand old merry party dragon(name redacted for spoilers), consider the fact that he essentially has 2x hp and that his skills make him hard to handle. If you want to beat him, you'll have to lay on the damage - there's only a couple ways to consistently deal dmg. One, I recommend clearing the field (don't forget to check the shop) of all that nasty skill stuff. Two, I recommend dealing damage fast and hard (I hope you've been using paladin, cause it'll make your life a lot easier here).
I had no real trouble finishing the game - not even with harvesting dragon meat (I got Dead on 1st, Water on 2nd, Fire on 3rd and the green one on 7th run). I had only been using the Wizard, Monk, Barbarian, Rogue and whatever-the-last-one-is-called (no Paladin/Druid/Bard except for the wounded goblin).
I can only offer a few tips about the Source (golden) dragon: have lots of mana (especially for the Monk), use Substitution, Exorcism and exorcism scrolls, eat Dr. Worms (30hp/turn). Don't use tile-based buffs/damage like healing, increased attack power/mana gain, magic mines or traps. Plan all your moves for every turn in advance (having good imagination and playing a lot of match-threes in your youth helps).
2) There is a secret final boss you need for 100% completion. Clue: Trying to get him to fight you might leave a bad taste in your mouth.
He gives you 104%. I got the completion quest before I defeated him IIRC.
= my thoughts. Ironically, it was the last skill card I got, right after killing the golden dragon. I have tried a couple dozen times on the lower-level bosses, but I had to go with a Mashina Soulmaster in the end (~110 damage/2 turns).
Has anyone found out or written down if and where ingredients drop? For example, I've been looking for a "magenta fish" (don't know the actual ingredient name) for both a page 6 recipe and to buy more recipes from the goblin.
The third key is not in map 1. I forgot which map it is in but I'm in map 4 in my second save and I still don't have it yet. In fact most maps have at least one section you can only access much later, just return when you find the required quest items.