Probably the wrong place to ask but
What's the best way to set up Photoshop for your art and workflow? I'm a Sai fag and and have barley used PS for drawing, and I want to organize the UI as best as possible.
That depends entirely on you and your workflow. Not everybody paints or draws the same.
Do you even have a workflow? Are there a set of steps you use to create a drawing? If so, let that be your jumpoff point. If not, maybe get a workflow before you look to start optimizing your workflow.
Like I said I'm a Sai guy, so I'm used to much more simple tools. I'm wanting to use PS for more paint studies and working with values. Sai has methods for that sure, but PS seems to be a better too from what I can see.
I'm thinking it's just a case of what >>2249689 said and just use what's necessary, but I'm not entirely sure what is and what isn't.
Set it up like the pic you posted in OP, but get rid of the Adjustments panel on the right (if you need an adjustment layer you can use the circle split in two at the very bottom right of the screen that is between the masks and layer groups). I would also change the sliders to either HSB or LAB instead of RGB, but that is personal preference. I usually open up a navigator window and put it on the right side where the adjustments window is right now, and that way I can always see my image in thumbnail view. Some people like having the brush window out so you can modify brushes on the fly, but I don't bother. I found it was easier to just organize my brushes in a way that I have all that I need at my disposal.
It depends. Here is my setup for example, it's a clusterfuck on the right, but I use Tab to temporary hide the cluster while working on certain layers.
Still using CS5 here
I use that and the right click menu and ctrl-alt-click & drag (alt-click & drag on Windows I think).
A GPU would help. Doesn't have to be a top of the line GPU.