For Adeptus Evangelion, we're not going to play the game of Carrier load master. For your purposes it's a mobile airport: all of the VTOL's and specialist aerial units your heart could dream of may be maintained and launched from within. The only exception would be the Evangelion Carrier aircraft, which are simply too big for it and take off and land from Daedalus. So at least if you lose the carrier you can still airdrop EVAs around.
No tanks! (lol) Instead, what you'd get as an equivalency would be additional Rapier Frigates. Turrets, on the other hand, are completely fair game and are the way to go if you want dug-in ground defenses on Ark itself. The two problems that Turrets have is that the good ones are unlocked via research because they use the same weapons the Evas have access to, and then the BIG problem of Ark's size. Rather then going for a single city map Ark is going to consist of about 5 major districts (off the top of my head: Daedalus Aerodrome, Prometheus Lab and it's environs which you're about to see firsthand, the Hydroponics farm area, Central City with the seat of UN civilian government, and finally the main Downtown area and the Towers). Placing turrets to cover all of those areas will be tricky... My current thought is to perhaps allow Turrets at a discount due to the difficulties of city coverage, or make them "quantum" turrets that spawn in multiple maps somehow. Maybe they will be set up on a Rail system of some kind, as you can sort of see in Rebuild.
The UN Navy has the versatility of heavy firepower and the mobility to be relevant anywhere on the map, and even in adjoining islands if you manage to intercept the Angels before they reach Ark. But what it lacks is expendability... getting replacements for something like the Oklahoma might cost you a pretty sum in terms of "Requisition Support" points (you might have to buy the Talent something like twice for it). And replacing the Carrier would probably not even belong in the same category... I would consider the cost of that to be a Political or Military IOU.
By the time we get around to spending experience and surplus and you can consider upgrading your arsenal, I'll have some alternate vessels and aerial units for your consideration. Current thoughts include dedicated ground attack bombers, an AWACS observation plane that will get you bonuses on the Angel Detection chart against certain kinds of angels (this would likely be an unlock of some kind), and some kind of AEGIS battlecruiser (basically a dedicated Anti-Air Gunboat).