Great question. I don't exactly see pictures. My visualizations are kind of abstract, picturing shapes moving around sometimes. Other times its just I "know." Best example of this is when we first walked onto the property that's our house, there was a 125 by 275 food back yard with a few dead trees and lots of weeds. But in that moment I had a brief mental flash of the finished yard, pretty much as it is now, with trails, dry streambed lined with rocks and an island shaded by trees. When I started working on it, it was pretty much plugging in parts that fit the picture.
I generally start projects from a rough drawing. I might fiddle with details of the drawing, but mostly solutions bubble up during sleep, or that time when you are nodding off. My noodling with drawings are generally to work out how to make the jointing work, and to work out and record measurements and details I might forget otherwise. Sometimes it helps work out the assembly sequence.
I write a lot, mostly non fiction, and in considerable detail. Way back in my newspaper days, I realized that if I forced the writing it was generally lousy. So if possible I'd wait a bit until I got that flash and the story was ready to write itself. This was especially effective when I'd interviewed someone. I no longer write against deadlines (for the most part) but my best stuff always bubbles up like that.
The creating process is really a verb, not a noun. In other words, it is a live thing that occurs mostly in flashes. I isn't something ground out with internal self talk as if it were a narrator. A very long time ago, I did nontheatrical, 16mm films. I had a gift for forseeing how the shot should look and how all the shots should be done to make good continuity and flow. Again, it was more knowing than pictorial visualization.
The thing I like about woodworking is that it is solid, three dimensional and when its done, you have a thing to touch and use. Most of my life, my output has been ephemeral, temporary, or the production of someone I've coached or consulted. That is satisfying in its own, and very different way.
As to brain power, I've found that you can tell a lot about intelligence by the way a person moves or leaps from one thought to the next on a theme. The most intelligent people I know hear an idea, then leap two or three leaps ahead on the implications and possibilities that emerge from the first input. An IQ of 100 is about normal, and really is sufficient to do nicely in life. About 160-170 you start finding weirdness popping up.
One of the great influences in my life is reading Krishnamurti, an Indian teacher who steered you to the realization that most of what we call thinking is more like rumination; spitting up old ideas and notions instead of just being present to what is right in front of you. Not adding your prejudices and opinions and fixed thinking, which is what murders creativity and originality. Keeping the idea open for some time is where the unconscious mind gets to work its magic.