Interesting points. I feel we'd almost need a new branch of science, Astrochemistry to get to the bottom of what forms life could take. Non-carbon may still have to be made up of an element in the same group such as Silicon due to its versatility. Huge sentient rocks, maybe even the size of a planet or perhaps sentient asteroids that bypass all our detection of life. I feel advances in chemistry will be the key, we need to know exactly what each element is truly capable of under the different conditions.

The idea of fifth dimensional beings existing outside of time that are almost able to 'look down' at us from above, the same way a 3 dimensional being can physically look down at a 2d being or flatlander, is an amazing thought. The possibility of biological life experiencing time non-linearly is concept I find fascinating, they would be able to know when they die and flit between any point in their lives but their body would still be anchored in one physical point in space. Or that's just one possibility.