A red icon means that the user can kick other users off. The options icons indicate whether or not the user wants to receive private communication. If there are no icons, you can send private messages and chat invitations. If there is a Refuse Private Messages icon, you will not be able to message the user. If there is a Refuse Private Chat icon, you cannot invite the user into a chat.
More details are available in the manuals.
The Hotline Client and Server uses it's own protocol to communicate with each other. Therefore, you need to specify in the HTML anchor tag that it is the hotline protocol that you want to use. Please note that, at this time, this does not work with Netscape on the Mac platform.