I don't own a Carrack, and don't plan to in the future, since I am more a Polaris guy, but right now the Carrack is certainly my favorite ship in game so I'll pretend for a moment I was outfitting one.
First thing. . .I believe in ballistics. I do not believe in shooting people's shields when you can be killing the target from the start, so I gotta say Revenants all around. You can carry extra ammo, and the point of this bird is not fighting. The guns are defensive, but you do want to kill targets as quickly as possible and so again I am urging trigger control and max DPS with min energy budget. Experiment with and find the failure rates with overclocking the guns. 8 Revenants do 5,400 dps. Overclocked they do 8,100. If 40% penetrates shields, that's 3,240 damage to hull with shields at full. That will kill a SuperHornet in 3.1 seconds.
Secondly, shields. Many want to go for the Parapet for max shield value. I think the refresh rate of the FR-86 is so extreme, that it is the better choice. Just needs you feed them ample power. Combined they refresh 8,700 which means if your attackers are flying energy weapons, odds are good they can't much hurt you. Think about how many weapons need to hit every second to beat that refresh rate, and you can shrug off half dozen Buckies without breaking a sweat.
Third, Q drive. This bird is meant for deep exploration which means efficient Q Drive. Even though travel times will be longer, you will go farthest with the Agni. Unless you are with other ships, I would opt for the longest range possible. That's the Agni.
Forth, reactor and coolers. Hardpoint says the stock reactor and coolers on the Carrack are sufficient to power everything in the loadout I'm describing here, with just a 10% safety margin. That's good and reason to save pesos on these. Leave 'em stock and test for yourself if you have power management or heat troubles with any given loadout. HP shows Revenants drawing more power than Attritions, and you can bet that is not correct. So field test to be sure. You may choose to upgrade the coolers even if the reactor is fine, just so your engines stay cool when overclocked. You can increase your cooling by 70% with the CoolMax, and probably leave one off during touring for lower EM sig. It is possible that overclocking the engines will draw so much power the stock reactor is inadequate, but I tested this with everything on, including spooling the Q drive, so I doubt you'd need to swap out the reactor.
Fifth, engines. . .the Carrack is astonishingly fast for its size. Since you can do your own repairs and maintenance, I think it is going to be worthwhile to overclock the engines to get extreme speed. My guess is, any attackers could literally be run down one at a time with all 8 guns. I think this is a case where the best defense is a good offense. Select targets and chase them so all 4 turrets come to bare at once, and eliminate opponents one at a time. Most fighters will not last past 3 seconds. This ship is fast enough to chase down most fighters! Use that speed to stay safe, but also to alter the odds in each moment. It is far easier for a turret gunner to hit a target the ship is chasing (or that is chasing it!), than one that is crossing its horizon. IIRC, gimbal assist works with turrets too. If that's so, and the pilot gives the turrets easy targets, you have every reason to expect to hit. It's especially useful to think of this as a preferred tactic in case you're attacked by a Sentinel. Early reports are the Sentinel's EMP is 100% effective against the Carrack, so killing any inbound Sentinel immediately is really important. Just stay outside its 1,200 meter pulse radius.
Important point to note here to my brothers at TEST: the Sentinel is the Carrack Killer, but if things stay as currently and reports are accurate, even an overclocked Sentinel cannot catch an overclocked Carrack. If a Carrack turns and runs and a Sentinel with a charged EMP chases it, the Carrack will control the engagement and can kill the Sentinel quite easily. The Sentinel has 23,460 hull. If it chases you, It will take min 7 seconds to kill it. IF in worst case scenario, it has fixed ballistics chin mount and doesn't ever miss, it is doing 5,734 total damage in that time to your stearn and it could scratch you, but no one flies a Vanguard like that; and the Carrack has 127,500 points hull. He can't hurt you much. He might damage an engine. It's really important to know how to sucker a Sentinel behind you, meaning you need to know exactly what your ship can do. For example, you need to know exactly how long it takes to get up to speed from a 90* turn. If you're flying a Carrack and a Sentinel comes in on your beam, you need to know if you have time to turn away and control his distance behind you. If you're flying a Carrack and a Sentinel comes in on your bow, you should QT out of the engagement. I'm saying this because lots of Sentinels have already shown they can own the Carrack, given a dopey Carrack captain.
Additionally, chase a friend flying a Razor and see if he can out-turn you in small enough time to escape. You can't stop the Carrack skidding through turns, but if you can keep the nose pointed at an agile fighter long enough to kill it, all well and good. If not, look at overclocking the rotation thrusters.
Sixth, hangar. . .Pisces. You can't fly this effectively without being able to shuttle people.
Last, garage: Razor EX plus 2 X1 Force bikes, riders with sniper rifles so they can scan distant areas.
Bonus: the 3d Radar Holoviewer--in an engagement, the bridge has to direct fire since the only person who knows the situation is whomever is watching the viewer. He's giving directions to the three manned turrets, the remote turret and the pilot. Attacking fore and aft is preferred but 3 of the 4 turrets can fire at once on any attackers amidships. I'm convinced that effective combat crews will coordinate their attacks using that viewer. Don't ignore it and tell gunners to fire at will. That's allowing your attackers to define the battle for you, which is the short road to failure.
Unknown: what sorts of drones can we use to add to all these other capabilities? I think the drone room is going to prove exciting and could change any/all of the above. Can we use drones to explore caves? Can they attack? Can they be used to broadcast fake ship signatures? Can they haul cargo boxes terrestrially? Only time will tell.
Such a very cool ship, and the best reason yet to join a merry crew of madmen!