1: How do they perform over say a fleet assault cruiser refit or the new arbiter battlecruiser?
2: Is it worth getting the full pack?
3: Can the 3 ships combine to look like a typhoon battleship npc or close too? [pictures please

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4: whats the overall benefit to using a command ship?
Comments
One of the better reasons for obtaining the command cruisers is the "All hands on Deck" trait that you get at level 5 mastery. It's from the Presidio variant, not sure if it's the same for the other two. I've not looked that closely at them, maybe some else can clarify that point. As for comparison against a (well built) Arbiter class, I couldn't say, every one I've seen in pug groups either radically under perform, or take the definition of a class cannon to a whole new level. Again someone else may be able to provide a better insight.
Assuming you build yours similar to mine, and again assuming you are missing the doffs I have then it's going to be pretty expensive to kit out, and that's not factoring in the upgrade and rarity costs. and by expensive I mean well into 6 zero's ec wise. if you go the Very Rare doff route.
Pretty much all 3 variants are superior to the FACR. Comparison to the Arbiter is a little harder, it depends on your build and style. The Aribiter with it's 5/3 weapon layout and better agility is a little better suited toward front facing builds using Cannons or Dual Beam Banks. The Presidio is more inclined for broad side 'beam boat' style. Not saying the Arbiter can't perform as a beam boat because it can. The Presidio and Fleet Arbiter have the same console layout, the Presidio can take more of a beating, the Aribiter might do a little more damage. The Arbiter can use the Weapons Systems Efficency command which is nice, the Presidio has a hangar bay. The Presidio is also 500 Zen cheaper since it's Fleet Quality from the start. The Arbiter requires purchase of the C-Store variant (3k Zen) for the Trait and console and an additional 500 Zen for a Fleet Module to upgrade to Fleet quality.
Honestly, no. Unless you really want the visual customization options, the Presidio is the superior ship. I have the 3 pack myself, I don't use any of the 3 consoles. The Presidio has the best BoFF layout and the vastly superior trait. The Geneva is also is a good crowd control style cruiser since it can slot Gravity Well. The Concorde is completely useless outside of visual options.
No. It has a lot of customization options with the 3 pack, but it doesn't look like a typhoon.
I don't know that there is an actual advantage to picking command, it's just what best fits your style. For me personally, I like how well rounded and versatile the Presidio is. It does everything and does it well, it hits hard (mine easily breaks 40K+) and can take a beating as well. It's very agile for a large cruiser as well, especially if an RCS console is used. It should also be noted that if you use 2 of the command consoles (The Samsar console also counts) the 2 piece bonus is an RCS boost that makes it even more agile.
For a FAW 'Beam Boat' it's my 'go to ship.' I'm quite happy with mine and would definitely recommend it. If you're interested to see how mine is set up, the build can be found here:U.S.S. Vigilant
Typhoon look? No, impossible, not at all.
http://sto.gamepedia.com/Typhoon
http://sto.gamepedia.com/Concorde_Command_Battlecruiser
http://sto.gamepedia.com/Geneva_Command_Battlecruiser
http://sto.gamepedia.com/Presidio_Command_Battlecruiser
The hull, neck, the "secondary humpback hull," and how the pylons attach to that humpback instead of the engineering hull just make it look wrong if you want the Typhoon look. The more you look at the weird humpback and how the pylons attach to the ship, the more wrong the whole thing looks. You're not getting a Typhoon. You're getting Igor.
The rest of the ship is a mixed bag. The BOFF layout suitable for the TAC Cruiser role. It handles better than the T5 Sovereign but the Avenger handles better. The T6 Eclipse will dance around the Command FDC. It has full access to Command BOFF abilities which are rather lackluster as a whole. Also, if you intend to be dependent on energy weapons, Command FDCs lack "Weapon System Efficiency" Cruiser Command, a price they pay for having a Hangar Slot. That means no free, built-in -25% weapon power cost by energy weapons. I'm sorry, if I could, I'd ditch the dumb 1-Hangar Slot and get that Cruiser Command in its place.
But again, despite my derision of the Command FDCs, the TAC ship's "All Hands On Deck" is the true star of it all. I can rag on EVERYTHING about every version of the Command FDCs but that trait is simply fabulous. The rest of the ships can go to hell but the trait is a must-have.
How do they perform?? do you really need to ask?? enough good for a T6. Dont know what else to say lol, people will never realize that in this stage of the game any T6 cruiser will perform as any other T6 cruiser. There is not much margin of difference anymore between one cruiser or another. The only difference is the ship mastery, thats all. I only go for the asthetics when buy ships nowadays, its a bit "silly" to go for the stats, when you know they are almost the same as any other T6 cruiser.
No, you cant combine the asthetics to make the ship look like a typhoon. But the look improves a lot with the 3 variants.
As other said, the overall benefit of these ships is the mastery (again) and the defense capabilities. Using the 3-piece set gives you also the improved fleet plattform, really neat to keep your shields regenerating in the most difficult circunstances lol. And more than that the abilities and defense skills have a really neat cooldown. Also command cruisers are focused more to team play, and their abilities are more directed to team benefit than yourself. But that is just an addon the ship perform really well in any circunstance.
Again clicky consoles went straight to the bank and as Sqwished says the build could be quite expensive if you don't have all the relevant parts already, mine came from a long term build from my Avenger
I use the consoles on my eng cause I don't have much in the way of uni consoles for him, they are nothing special.
Command abilities are nice as well, not OPed (IMHO a good thing).