I also have the Attribute column hidden because it doesn't contain anything for normal tracks. The second column contains a lock icon if Analysis Lock is on for that track, and CUE if the track has memory cues or hot cues set. You can't hide that column.
If you click on the empty space on the left of the Preview column, it previews the track from the beginning, whereas clicking in the waveform itself will preview from that point. The empty space also contains a stop button while previewing.