Definition of a Corsair army?

We have the kabals, the cults, and the covens, all with their readily-identifiable components. But, how would you define, or create, a band of pure Corsairs?

What design or weapon elements would you use as a theme? Or which wargear or special rules would you focus on?

Would you use just DE, or would you blend elements from all Eldar, as befits their origins? Or would you use the FW Corsair bitz (or make your own)?

And which DE choices would you use for each slot?

I am still trying to nail down DE Corsairs myself. The Duke is the obvious choice for HQ, or at least one HQ slot, but Saintspirit has posed the interesting option of another IC that allows Scourges as troops.

I think that Scourges as troops would be very fitting fluff-wise, and hugely entertaining. The FW Corsairs are Jump infantry too, aren't they? I don't have their rules, are they a troops choice?

And Harlies as Elites, since their independent, roaming lifestyle would also be a good fit.

Reavers for FA and Raven Strike Fighters for HS. Venoms would be the perfect transport, but what to put in them?

This would be an incredibly fragile force, but that would be true of real Corsairs, wouldn't it?

By all descriptions - COrsair armies are too varied to have a clear and cohesive theme. I think they can be built both from Craftworld Eldar as well as True Kin.

I'd say you're probably on the right tack that they would tend to feature more fast strike type stuff than any heavy elements.

I would tend to expect them to lack Coven units, and (if Craftworlders) any Wraith units. Other than that I see it as fairly open to individual interpretation - and frankly could see Coven pirates...though I may choose to stand by lack of Wraith units...also lack of Avatar, natch.

I agree with Thor about the probable lack of Coven units. Personally, I would restrict a Corsair-themed list to the following units:

HQ: Duke, Malys, Archon, Succubus, Court
Elites: Trueborn, Bloodbrides
Troops: Kabalite Warriors, Wyches
Fast Attack: Scourges, Reavers, Beastmaster Packs
Heavy Support: Ravager, Razorwing, Voidraven

Every unit that can take a transport must do so unless your Archon is carrying a Portal.

The forge world models don't have rules yet, I think they will be a troop choice when they come out. They are supposed to be part of corsair list in Imperial armour 11, suppose to allow mixing craft world, dark eldar, and some new corsair units.

So, dark eldar corsairs would be like posted above, mixed eldar is fw list.
Craftworld are probably autarch(as corsair prince), warwalkers(feature in fw list since new models are made by fw for corsair varient), flyers(a few apoc formations mention corsairs), guardians, rangers(said to travel with corsairs in fluff) and support platforms(read somewhere this is corsairs favored heavy weapon platform).

I think an obvious statement would be to wait for the new Imperial Armour book which is just around the corner: it will have mountains of fluff on the Corsairs and of course a full army list, ie rules etc.

I'm not a massive fan of the direction they have taken with the Corsairs, they're very much a retro throwback to the original Eldar of Rogue Trader with a slight twist whereas I prefer the less uniformed, dandy look that was shown in the 4th edition rulebook.

However I am using a unit of the new FW Corsairs to make a squad of Trueborn for my Sky Serpents army. Their background is being dreamt up as I type.