I disagree with your final point, that it is unlikely that it would be possible to get information other than "something occurred at around a specific area;" however I agree with your other points.
A detailed computer is likely to be very unstable. Even if it could collect lots of information about the environment reliably at a distance, it would not be able to retrieve or utilize that information quickly.
In a large enough board, however, we would expect to see a computer that was essentially isolated except for a few small stable patterns which it would be able to interact with via radar.
Presumably a sufficiently intelligent AI would be able to better configure the patterns of life, perhaps using some kind of protective membrane.
However the chance of creating a life board of such a size and with such a distribution that one would expect to see ONE such AI and not a thousand or more (which would likely have different goals and levels of intelligence) would mean that rather than expecting to see one type of complex computation take over the board, I might expect that in the limit (i.e. in a 3^^^3 board; after about 3^^^3! time steps) to see extended wars between the most intelligent AIs.
Unless it turns out that there is an unstoppable self-propagating "virus" in the game of life, which would be a somewhat depressing thing to learn!
What happens when two copies of the virus meet?
Conway’s Game of Life is Turing-complete. Therefore, it is possible to create an AI in it. If you created a 3^^3 by 3^^3 Life board, setting the initial state at random, presumably somewhere an AI would be created. Would this AI somehow take over the whole game board, if given enough time?
Would this be visible from the top, as it were?
EDIT: I probably meant 3^^^3, sorry. Also, by generating at random, I meant 50% chance on. But any other chance would work too, I suspect.