Welcome to Librarium Online!
This is just a rough-draft, there will be a doubles tournament, I will probably be allied with Al Rahem with lots of meltas and flamers, this is the list, or some sort of it that I want to take.
HQ - Vulkan
two 10 men squads of marines in drop pods with minor upgrades, Vulkan is joining one of them.
Elite - Dread with melta on a pod
2 Deathwind Drop pods with whirlwind launcher,
1 deathwind dro pod with an assault cannon.
/this comes out roughly at 1000 points
I drop first securing objectives etc... when enemy will arrive( if he is not there yet) I drop deathwinds on him to thin his flanks.
Rahem with his buddies come out from outflank with flamer and melta goodness (linked because of vulkan) and clear what is left.
Telling us what sort of minor upgrades your tactical squad has would be highly useful. Also I'm pretty sure Vulkan won't give your allies rerolls on their melta/flamer weapons. having that sort of in-your face approach of drop pods combined with IG sounds pretty impressive. Just make sure you don't cut out all your ally's firing lanes with your drop pods!
You can use Deathwinds? Aren't they Forge World? Better check with your Tourney Organizer before your opponent objects.
Alzer is right. Vulcan's ability doesn't cross over to another army. Whereas if you ally sisters to your army, it is ok because it is still 1 army and they share the same FOC. However, here your IG allies are a totally separate army. You might want to check with your TO on this as well.
I also was thinking about the idea.. a full inquisition army, so I would buy some space marines and deathwatch conversion pack, and mix-n-match them with sisters, saying that they are all inquisition space marines, would give great fluff to the army and look will be very unusual.
I already have couple drawings of an inquisitor with a relic blade and a heavy flamer... looks like a small crisis suit =)