If you are trying to keep clutter down, you might consider holding off on a sink bridge. I often sharpen on a piece of shelf liner on the side of the sink. It is a bit messy, but cleanup next to the sink is easy. I recently started using a homemade sink bridge (made out of a scrap of 2x4), it is nice, but it is another piece of clutter to deal with.
As far as stones, I have limited experience with the stones you have listed, though all are highly thought of. I do have the Green Brick and it is a great value for the money, but it is soft and dishes moderately quickly and I am starting to develop an appreciation of harder stones. To that end you might lean toward the Shapton Glass, Shapton Pro (the Pros are a particularly compact solution), or the Nubatama Ume line. I do have the Ume 1k speckled (http://www.chefknivestogo.com/nubatamaume1k1.html
). It is much harder than the Green Brick and cuts extremely fast. It is a near splash and go stone so almost no soaking is required. It feels coarser than other stones I have used in the 1k range but leaves a nice enough edge and gets there quickly. CKTG is out of stock on that stone at the moment, but you can contact Ken Schwartz on this forum and he has some. Unfortunately, I cannot personally vouch for any of the finer stones because I do not like the finer grit stones I own (don't worry, you are not looking at any of them).
As far as a flattening stone, you could consider saving some money up front and using sandpaper on a trued surface. Over time it will likely cost a bit more, but in the short term it is cheaper and there is not an additional diamond plate to keep up with, just buy a pack of sandpaper, use and discard. It is likely you will appreciate having a diamond plate in time, but this is one of those items that you can get by without if need be.