Sure, but there is a prioritization system involved where the highest payer gets pushed first. So the AI may detemine you like X, but if the buyer only showing Y, you'll get to see ads for Y and no X.
It is different. Rules and laws are supposed to make sense, but the one with 10 mph is not. There are limita to 250 kph in Europe and I dont see car dealers going down. Also, for years there are emissions regulators that make life hard for auto makers, but they obey and still sell cars.
They are including Eth, not switching to it completely. They will keep the CAN buss there as long as it makes sense.
Instrument clusters with graphical display output do use the Eth more and more because the amount of data beats the capacity of a CAN bus by far, but devices without big data transfer needs will stay on CAN. For example, what need is ther for Eth for an electronic gear lever? Not much data being exchanged.
Not sure what you mean by "not bridged across them", but devices on different communication busses (CAN, Flexray, Ethernet...) do communicate with each other through these devices called "Gateways".
SecOC is based on symmetric key cryptography. If an ECU is replaced and has a new key, this key will have to be taught to all other ECU's in the vehicle communicating with it.