Looks like the base model has 4, S3 remote turrets. The Military transport adds a single S3 chin mount. The gunship adds 4 more turrets some of which are S4 and S5.
They balanced the ship by limiting the arc of fire from the turrets, so the three forward facing turrets cannot fire on the same target when it is significantly off center line, and a single player cannot control all the turrets himself (as always).
Not loving these choices, especially in light of what was done with the Hammerhead, which seems this gunship's closest comparison. This ship will have better cargo and range, but it should have better guns, IMHO. S3 mounts are too small for a ship this size, but these are the kinds of things prone to change so who knows? The thing for me is, what can you put in the bird? What can you install in all that cargo space beyond ordinance? Can you turn the gunboat into an exploration ship, EM Warfare platform, stealth incursion platform, etc.?
https://video.search.yahoo.com/yhs/search?fr=yhs-adk-adk_sbnt&hsimp=yhs-adk_sbnt&hspart=adk&p=Star+Citizen+Starlifter#id=2&vid=8e81224ecdef682db51da8f00e9c4f9f&action=view