Sounds good. I'd I think do something slightly different with magic items, but only slightly (I don't have the DM kit either).
Good suggestion. It just gets a tad complicated for the writers of the adventures to figure out how much treasure we should give out.
Do cold iron tipped and silver tipped arrows count as "uncommon"?
In 4e parlance, 'uncommon' basically means "It has a power that can only be used once per day." The logic is that, PCs can easily buy or make tons of common items, but they can't do that with uncommon items because it would let them stockpile a lot of one-use powers, which would let them 'go supernova' if they used it all in one encounter.
And 'rare' items are basically 'distinct' uncommon items, like it's not just a flaming sword, it's Asrabey Varal's flaming sword that can also change into a whip and be used to grapple the ceiling or walls.
So yeah, you can get some extra gear at the end of the adventure. Since we're not actually rolling for combat, some of the specifics don't matter too much, but at the start of the second adventure you'd all basically have a magic weapon (or implement for spellcasting), magic armor (or magic clothes), and a magic cloak/amulet which aids your non-armor class defenses (Fort, Ref, Will). There's really not a huge variety of powers available at low level, but you'd have a few extra tricks thanks to the magic items.
As for out-of-combat equipment, a length of gold wire (enough to make a circle, say, 15 feet in diameter) could come in handy. And would it be possible for Carlao's sword to be made of cold iron in order to make it effective against foes like Asrabey, or would that diminish its strength? I like Gaethan's suggestions, so I'm just thinking of how Carlao might mimic those.
In 4e, I don't think there's any mechanical use of 'cold iron' over anything else. Since some magic weapons will be made of pure lightning or spinal columns and stuff, they ditched special materials as something separate from the item's specific properties.
There are 'feyslaughter' weapons that prevent teleportation, and an actual 'cold iron' weapon that immobilizes and does extra damage against fey creatures on a crit, but both are at higher level than you can get now.
Also, at some point Carlao might want to take shooting lessons from Josiah (maybe learning to use a rifle - taking a feat for proficiency). He wouldn't plan to ever make firearms his main weapon, but since he respects Josiah, Carlao would want to show some interest in Josiah's interests. And you never know when being able to hit something at range (despite Carlao's unimpressive Dexterity) could come in handy. So, at that point he would requisition a rifle and some ammunition.
Muskets and pistols are simple weapons; they're just very slow to reload without the proper feat. Rifles are superior weapons, and require a feat to use properly, and another feat to reload rapidly.
), a cloak (or clothes armor, but I think a cloak is just "cooler" 
, and the specially tipped (or magical) arrows for "unusual" foes.
