Re. your second question, I am not sure what there is to be discovered in seeking an answer to that. There is no necessary correspondence at all between the form of a symbol or representation and the thing it represents. For symbols to be useful, they just need to be consistently related to the things they represent.
As for what the 'really real world' is ultimately comprised of, this doesn't have much importance for the psychology of perception, imo. If you're a materialist, it's made up of particles, fields, forces etc. If you're an idealist, everything might be thoughts in the mind of God.
It doesn't really matter. I'm just glad I have a visual system which won't suddenly decide for laughs to make speeding cars look like floating marshmallows, or rotten food look edible.