2 Campaign Ideas that need help / advice

[Adun]

First off, if any of my players read this, I will have rocks fall on your character. You have been warned! (JK... mostly)

For background:

I am running a homebrew campaign set in Golarion. The timeline is a bit different, but mostly the same between this version and cannon. The players are mercs hired with their company by the pathfinders to hunt down a group of Orcs that raided the lodge, stole several thassilonian artifacts, and then torched the place. Most of the pathfinders made it out, but while the majority of the lodge relocates to inform the other lodges of what happened, a few have hired and are travelling with the merc company.

So they go into Belkzen, encounter some unusually intelligent Orcs, and have some interesting combats where tactics are used to great effect to harass the party. Some stuff happened, and they wind up in some dwarven vaults under Urgir.

So my first problem is that I've mapped the small dungeon out, but apart from some traps, I haven't really populated it. I have an idea about some dwarven ghosts, but the party is level 4 and don't yet have funds/opportunity to get magic weapons, so I don't know how well they'd fare against incorporeal creatures. Another thing is that I want them to have to figure out a puzzle involving the four vaults on this level of the dungeon before they can descend to the final area and reach their goal, but I'm running out of ideas.

Secondly,

Spoiler:

I plan on running Curse of the Crimson Throne after this campaign, as a follow up story-wise. I even intend on their merc characters showing up to help in Book 6. This isn't so much a problem as it is asking for opinions on storycrafting. I plan on replacing the BBEG of Curse with the BBEG from my homebrew, a Thassilonophile Teifling Enchanter who seeks to become the vessel for Sorshen's resurrection. The timeline between the first campaign and the second is a matter of months, with the Enchanter using her considerable abilities to weasel into Illeosa's court and then kill and replace her with a thralled Illusionist puppet. I guess I'm asking if this messes the story up in serious ways from what is written in the path?

[Adun]

Oh and the party composition is as follows:

Archery Ranger (Douchey and proud of it)
Summoner of Eldritch Abominations (Ia! Yog Sothoth!)
Magic Item Crafting Wizard (Combat spells? Why would I prepare those?)
Cleric of Sarenrae (Why is she even here?)
Paladin of Torag (Half-orc. Not stupid, and not Lawful Stupid either.)

[Snow_Tiger]

By level 4 the martial characters should probably have something magical

[Snow_Tiger]

Also there's a thread out there about puzzles and riddles to use in rpgs

[Alarox]

I was just passing by, but here's an idea for the "four vaults puzzle".

Write an interesting riddle that relates to the following puzzle. Have the players see the riddle and try to understand it. In the four vaults, have four different enemies that link to the riddle in some way. Have the door only open when the four enemies are defeated in the correct order.

You could have the riddle filled with strange words that require knowledge checks to understand (or linguistics or something). If they fail those, then they would need to use trial/error to defeat the enemies correctly where, if the correct order is being used, the enemies do not respawn. If they're defeated in the wrong order then they respawn.

Edit, this one is an addition:

OR, the enemies start out as incorporeal dwarves until a magic "switch" is activated, then the ghosts reform. The ghosts respawn and become incorporeal if they are not defeated in the correct order.

That's the best I have.