Pieces are shown wet to show a more natural coloration. The measurement for each piece is listed there next to the picture in the LxWxH format. Pieces are measured from the widest points which is usually a thinner branch. So if a piece is only a few inches to big for your tank it can usually be trimmed most of the time without loosing any of it's style. Trimming can be easily done with pliers, snips, saws, or even scissors.
Pieces will usually sink in 3-4 days on average depending on their size.
Any questions at all please don't hesitate to ask