“Cheap drone” doesn't need to be off the shelf quadcopter drone, fixed-wings custom drones like the Iranian Shahed 126 are still dirt cheap compared to typical anti-ship missiles.
But you don't need one sensor per drone, but one per swarm with the same target (and any kind of data link between members of the swarm). And by the time the swarm is within reach of the protection weapons of the target, it's probably close enough for the fairly basic sensors onboard of every drone to be able to work on its own if the target drone is destroyed (for instance: GNSS up to the last know position of the ship, and then just computer vision at close-range).
A ship isn't exactly a small target. You could probably track it just fine with a satellite and update the target GPS coordinate of the drones manually. An aircraft carrier only moves at 55 km/h maximum.
Nope. Ships are very small targets in very large oceans. Have you ever even been on a boat out of sight from land?
Reconnaissance satellites will be the first casualties in any future high-end conflict. Modern militaries have to plan around the expectation that their space-based platforms will be unavailable or severely degraded.
Radar ocean reconnaissance satellites can detect ships under any weather conditions but they are are large, heavy, expensive, and can provide only intermittent coverage. Smaller satellites with optical or IR sensors can potentially provide more coverage but are less effective at night or with clouds.
And sure, you need to wait for a clear day, but that doesn't seem like too big an obstacle. Also, while space-based platforms will be targets, it's unclear how effective counter measures are. Identifying targets is challenging and deploying replacements is worth the cost if you can eliminate a large portion of an adversary's naval power.
This is nothing new. The USSR was tracking US aircraft carriers via satellite since the 1960's. China is only now catching up.
Carriers are certainly vulnerable to an extent, but detecting one with a satellite is only one step in the kill chain. Carrier strike groups already carry some limited anti-satellite weapons that can hit targets in LEO. There is an active arms race underway by the superpowers to boost those capabilities, and also (as you stated) to develop a prompt launch capability to replace satellite attrition losses within hours rather than scheduling launches years in advance.
That's basically how most Anti-ship missile work: you give them GPS coordinate for the rough location and then the missile uses an active radar homing system for terminal guidance. (You want the missile to keep quiet as long as possible anyway, to avoid being detected and reducing the time the crew has to react to the threat).
Apparently, the oceans do a lot of radar scattering that makes it harder to spot ships from the guidance systems of missiles. Not sure what the state of the art is nowadays though.
