Depending on the weapon type, make sure carriers don't go trying to pick a fight with a cap ship 1 vs 1.
They don't/won't. I'm not changing their role type, just adding a little pop gun for the human player who moves them closer to the fight.
Is there a way to keep the AI handling of carriers and their attack priorities (which = zilch as they leave it up to strike craft) the same so they don't commit suicide?
Yeah, by not changing their role type and leaving auto attack off.
All of this while giving them some defensive capability tweaked with hp / shield numbers?
HP and shields are easy to do as well, but from what I've seen, they don't need that tweaked. The recharge/repair rate maybe could use a touch of attention, but overall the numbers they currently have are fine and probably don't need any messing with at all.
Remember, this is a move to lessen strike craft not force the light carriers into combat. If you want to leave the carrier at the side of the gravity well, it'll still do everything it did before, just the SC will get picked off easier. Moving them closer is a risk versus reward scenario. You risk the ship at the reward of having SC pound on your opponent harder and survive longer.