With my grapheme→colour and word→colour synaesthesia, it’s definitely in my mind—when I look at the letter A, for example, my brain has the same reaction as if I were looking at a yellow object, even though I can see that it’s not actually yellow.

An upside of synaesthesia is that I have very good clerical accuracy, which is helpful for programming—typographical errors “stick out” because things appear the wrong colour. A downside is that I can’t really use syntax highlighting, because I find it distracting. This is what my terminal Emacs looks like: https://imgur.com/m76W8eF (with soft wrapping because there’s not really a line length limit in this codebase).

I can answer the second question, which is 'no'.