Lay out all the stuff you want to put in the new cabinet, then allow about 30% more space (unless you are one of those highly restrained folks who never keep both old raggedy gloves after buying a new pair, etc. :) When everything is laid out, then you can figure on how many hooks of what size (you can buy those separately), and how many shelves and/or drawers.

If it were me, I'd buy an el cheapo basic in wood, 2 doors and wide & deep enough to put buckets in the bottom section; finish it in and out with several coats of marine polyurethane and then add fake shutters and window boxes, or decorate to suit the locale, maybe decoupage leaves to look like a shrub... put in my own shelves since I like those movable sets of small drawers for storage, and maybe an inside cabinet just to have another door to hang hooks on. Guess I'm a fan of hooks, I think they are the next best thing to drawers.. For me overlapping doesn't work: when I want pruners I *don't" want to move 3 or 4 items to get to them, so I'm in favor of anything that lets me reach in and grab just what I want; I also like drawers that can be pulled out so you can get the stuff at the back easily.