The Display Options determine how the scene is displayed in the Character Tool. These settings are not saved in the character files, they are purely for preview purposes.
See here for descriptions of these options.
Here you can create and edit proxies for your character. See here for more information.
There are many properties that can appear in the Properties panel, depending on what is selected. See this page for details.
The Playback panel at the bottom can be used to scrub the timeline and provides playback options like looping of animations and playback speed. You can also change the timeline to be represented in seconds, frames or normalize the timeline from 0 - 1. The options gear offers further control on organizing how the timeline is represented.