On the first floor you should find 20 Ice Arrows and an Ether1. Equip Rosa with those arrows.

2F, a Bandanna right by the door. A Blizzard Spear in the first door, an IceBrand in the door to the right, and the middle door leads to 3F.

3F, a CatClaw right next to the door, an Ether1 to the right of the door, an Elixir right next to the left door to 4F. There are two doors that lead to 4F.

The right door leads to: Archer Bow, and a Life.

The left door leads to: a savespot, an Ice Shield, Ice Armor, and the door is in the upper left corner.

5F, Cure2, savespot, Ether2.

6F, leads to Dr. and Balnab. Fight them. Unequip Yang, and then go to the locked door on 5F. Yang will go away. Leave. You will enter a chase scene and Cid will leave closing the way to the underground. Go up to Baron.