The CMB is not a ring, it is everywhere and can be seen in every direction. It fills the whole universe like water fills the whole ocean. The CMB comes from the time of the early universe, when the universe more dense and every part of space was filled with hot glowing matter. As the universe expanded the matter cooled off and stopped glowing but the light from that glow continues to spread in all directions.

The speed of light only applies to matter and energy. Space is free to expand at any speed, it does not have any limit (that we know of). Yes there are galaxies beyond the cosmic horizon that are still coming into view. Although since galaxies are hundreds of thousands of light years across, it therefore would take that much time for one to come into view. We don't know how big the universe is but we do know it is at least several times bigger than the observable universe.

Wow, I can't believe you made a comic about the principal from my middle school