Leaf tower hint:
Complete the game, save the clear data, then head on out back to the map. Choose the Ruins of the Dragon Race dungeo, and watch the cutscene. Once complete, hover the cursor over the area north of the Fortress City Palladium dungeon, back on the world map, and a huge tower will appear--the Leaf tower.
Unlockable Mercenary Classes:
Unlock the following mercenary classes by performing the corresponding tasks:
CLASS - HOW TO UNLOCK
Druid - Requires level 20 magician and level 15 priests.
Hunter - Requires level 10 archer.
Minstrel - Requires level 20 hunter.
Musician - Requires level 20 paladin and level 20 archer.
Paladin - Requires level 10 magician and level 10 fencer.
Seer - Requires level 15 magician and level 20 priestess