If someone asks you how to spell a certain word, does the word appear in your head as you're spelling it out for them, or does it seem to come out of your mouth automatically?

Neither, really. For simple frequent words I remember each letter individually, but otherwise I either have to write it down using the mechanical memory to retrieve the spelling or I have to look at the complete word to test whether it looks right. I can test a spelling by imagining how it looks, but that's not as reliable as seeing it with my eyes, and of course writing it down and then looking at it is always best (short of looking it up of course).