AO allows you to view a server without picking a character; simply click the "Spectator" button at the bottom of the charselect screen. However, when you have already picked a character, you will need to type /switch (serverD) or /charselect (tsuserver) for the spectator button to appear on the charselect.
Ini files are used in AO to alter the game in various ways. There are two located in the root of the base/ folder, while the rest are associated with themes.
Specifies how often a "blip" is played. 1 corresponds to 1 blip for every character and 2 makes it blip every two characters and so forth. Generally, higher blip_rate = rarer blips.
Once you've installed the client of your preference (or the default client), you should know that all the characters are located in base/characters.
These are the idle and talking animations, they are labeled (a) and (b), respectfully.
This is where you place the button image of each emote. Each emote has a pair of images called button [number]_on and button [number]_off. The number is the number of the emotion in the char.ini file (you will see about it later).
Actually, this folder is just a folder everyone started to use as default, but you can actually use any folder name or no folder at all for this. Basically, this folder includes the pre-animations of an emote you can associate with.