Yes.Possible, but very tedious, right?
Not really. In fact, you can just not give them any, because they wouldn't be taking damage.Especially giving them food and water.
And since food and water's radius is big, you can put support facilities on the ground, or even feed them from the same facilities as the ones that support the "gate" guards.
Ranged units do exist. The pygmies that throw Molotov cocktails. Not sure if they come in regular raids, but I think they come in Halloween raids.And if they ever introduce ranged units, then it's done for.
But if your food and water supply lines are working properly, they will recover in due time.