Definitely go with the shelves between the 3" walls - you can do expedit if they fit, or bookshelves with movable height shelves (adjust height to the boxes or paper storage or what else you need), or closet doors with shelves behind them if you like to hide stuff away. for the table, I would probably do two separate - one for computer/cricut/printer (clean desk), and one work table (dirty/messy desk).
I also like the island idea - in my previous scrappy half-room, I had a short side of the desk flush to the wall, with two long sides and one short open for access and moving around - it was a half island and worked absolutely great!
If you look through idea gallery, you'll see islands mounted on Alex drawers from Ikea - those are absolutely awesome, shallow and long and wide (or narrow, depending) - would be perfect for punches and inks and stamps and cartridges and all the small stuff.
Good luck and don't forget to take pictures and share!