I'm diggin' this.
- The Temple
rank requirement seems intuitive, but there are a few considerations. For one, there are unique Buoyant Armigers in-game at Temple ranks as low as Novice. Additionally, there are even unique (named) Buoyant Armiger NPCs that do not belong to the Temple faction at all. This poses an issue of canon, and it depends on how closely you want to adhere to the original precedents set by both lore and game design (it's different for everyone, but I prefer to make my mods as close to vanilla as possible). The lore might not explicitly state that all Buoyant Armigers belong to the Temple. Or the devs might have forgot to make certain NPCs members. Not sure on that one.
- The focus of the
questline sounds good, but I'd also add at least a couple missions that involve escorting or protecting pilgrims. Perhaps a pilgrim has been kidnapped by bandits, or is in need of a bodyguard when venturing to the more dangerous pilgrimage shrines like Ghostgate or Koal Cave. From my understanding, protecting pilgrims is one of the core aspects of the Buoyant Armigers' philanthropy work.
- Expulsion for Vampirism is perfect, I wouldn't change it.
- The
favored skill list makes sense too. I'd stick with the five major skills + Restoration. Restoration is the only skill the BA preset has in common with the favored skills of the Temple. As long as that stays in there, the rest is gravy.
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Item rewards is great as well. Maybe even little to no compensation for the very early quests. This way the initiate could prove their selflessness and devotion to the order without expecting anything in return. Quest rewards could then increase in value on a sharp curve, culminating in a nearly god-tier artifact (on par with the Temple's Lord's Mail) as the final item.
- Another
meeting with Vivec is also a great idea. It could be implemented near the end of the quest chain as part of a climactic plot twist. It might also be interesting if a highly ceremonial meeting with Vivec was part of an initiation rite that Armigers of the highest rank must undergo. Maybe as part of the final quest to become guild master. It might involve the eradication of the Vampire clans as you suggested, or even putting the player in the middle of some grand scheme involving the Tribunal or Temple politics.
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Now, it might behoove you to segregate the work into categories (scripting, dialogue, NPCs, items, world building, etc.) and focus on one at a time. If you try to do everything at once, or chip away at each category piecemeal, it's bound to become overwhelming fast.
If you're planning on going forward with any world building aspects (for instance, adding a new BA fort/headquarters), you might begin there. Creating all faction NPCs might also be a good start. I find it's easiest to create all the "material" aspects of the mod first, and flesh out everything else later. I like being able to click on a cell and see the buildings or NPCs I've put there. Seeing such immediate physical results helps keep me inspired and focused in early development. But that's just the method I've developed. I'm sure you'll come into your own process.
Also,
scripting can be difficult and time consuming, and it's entirely dependent upon the complexity of what you want to implement. No matter what anyone says, writing your own from scratch
will require a deep knowledge of the inner-workings of MW scripting. I
highly recommend that you at least skim over
GhanBuriGhan's Scripting For Dummies. AFAIK it's the best guide to MW scripting out there.
You can also cut out a huge portion of time by simply copying pre-existing scripts whenever remotely possible (making minor changes where applicable). Just grab them out of the CS instead of writing your own. In this way you can accomplish anything that has already been scripted in vanilla without mastery of the language itself.
Oh, and the
Buoyant Armiger Stronghold is a pretty neat idea too. It's a bit more complex to implement in the way of the Great House strongholds, because of the various stages of development involved. But it would certainly be a great feature provided it made sense canonically.
In fact, what do you think of the idea of making the stronghold double as a Buoyant Armiger barracks? This makes more sense to me than a private home sweet home for no one's benefit but the player's. Based on the faction's ethics and resources, I don't ever see them greenlighting the construction of an entire stronghold just for one person (even the boundlessly relevant and special snowflake that is the player-character). The impetus for the quest itself could involve constructing a sort of military complex in some strategically relevant location, which the player could then "lord" over as the ranking officer. Maybe the faction wants to expand (akin to the Telvanni stronghold situation), or there is a need for an outpost somewhere due to some manufactured threat (vampires, ash creatures, heretics...take your pick). Something to think about anyways.
All in all it looks like an exciting project. I look forward to seeing how it progresses. Once there's a basic skeletal structure I'll see what I can do to contribute more as well. I'd be interested in a "creative consultant" role - possibly even writing some NPCs or quests. We'll see where this goes.