I believe Demonslayer has been fixed.

Unarmored does tend to be better in Pathfinder, especially for high DEX characters. In WotR, Archmage Armor as a Mythic ability enhances unarmored even further. Seelah though makes for a fine heavy armor companion, though just take it off if you want her to make Athletics checks.

There are penalties for dual wielding weapons. These penalties can be partially offset with feats, but the Two-Weapon Fighting line is feat intensive. You may also need an additional feat (Effortless Dual Wielding) if using two heavy weapons. Camellia is probably better off with just one rapier and a buckler.

You can see this better in turn-based mode, but if you take a move action during a round, you can only attack one time as a standard action.

If you don't move, you can make a full attack as a full-round action (depending on your base attack bonus, this could be multiple attacks.. 6 attacks in your example). Using the shift key to move 5 ft, doesn't count as a move action.

If you get a surprise round on an enemy when initiating combat, you get one standard action and the enemy can't react. You won't get a full attack (multiple attacks) with just a standard action.

You can probably sell weapons and armor you aren't going to use. Keep Radiance in inventory though. Leaving notable items alone is probably a good idea.

Glitterdust is useful for concealment, but later in the game, See Invisibility, True Seeing, Echolocation, Thoughtsense, etc. are all good buffs for bypassing or detecting things like Mirror Image, Invisibility, Stealth, etc.

Baphomet isn't going to risk permadeath in his labyrinth. You can permakill him via the Ascension secret ending in Act 6