The photo is of Robert More, on the left, and Tim Moyer, of Roseburg, on the right. Moyer and More are both surnames that are part of clan Muir (though Tim actually claims clan Gordon), so they're fellow clan members, both wearing the clan Muir tartan kilt. They are the same tartan design, known as the sett, though each is slightly different in size. Note that "plaid," as you are using it, is "tartan" in Scotland. There, "plaid" means a specific item of Scottish regalia, the large tartan cloth worn over the shoulder (larger than a sash) and pinned to the shirt or jacket in front with a brooch. You can see this plaid over More's left shoulder in the photo.
The "pouches" are "sporrans," used to carry virtually anything one might carry in a pocket — since kilts have no pockets. Both sporrans are "dress sporrans," as opposed to "day sporrans," and are typically either fur or with something formal — e.g., the coat of arms on More's sporran.
There's nothing particularly significant about the socks, and some kilt-wearers will go sockless (or anklets) in hot weather. But over-the-calf is traditionally worn for events such as Burns Night.
More's cap is called a Balmoral, and the color of the feathers is significant, white symbolizing one's being a Jacobite, or supporter of Bonny Prince Charlie, the exiled Stuart King who led the last Scottish rebellion against the English that ended with the disastrous Battle of Culloden in 1745.