Ok about the GUI:
what you mainly want to present are
-actions (spells)
-Items (inventory)
-chat
-the map
-character info
-quickoptions
Try to keep all actions/items/options slot (the selectible components) in a consistant style.
WOW did that by making everything same-sized squares, on wich the player can shift round items/actions.
most of the time only actions/chat/quickoptions/ and map are needed,
the inventory can be turned on and off.
I would (during development) use a placeholder artwork for the GUI on purpose.
Just use grey slots with very simplyfies black/white icons. So you can quickly adapt your GUI when you feeld like changing it.
People should see that it is NOT the final style yet. So they can keep imagining how it would look like and give suggestions.
Make the GUI components big enough though, without making every element in a totally different design.
And blend out all elements wich are not used repetatively. (just put them on a panel, that can be turned on and off, so you dont
cramp too much on the screen at once.)
-> the icons arranged in a circle for example are very hard to guess what they are actually, and use quite a lot of space for
beeing so small.
If you want a “selector” just make 3 Buttons, wich clap out the selection then.