A bot is an automated client which is connected to IRC, and is not directly controlled by a person. A bot responds to predefined commands with predefined actions. Some bots protect channels from floods and takeovers, while other bots are programmed TO flood and takeover channels. There are other bots which are used simply for entertainment. Bots are available in many formats, ranging from the simple and often temporary mIRC script,to the complex and powerful eggdrop.
NOTE: Any and all bots programmed to flood, takeover, or engage in abusive activity are banned from DALnet. Any attempt to run them will result in a kill and/or AKILL.
In most cases, the answer is "no". DALnet's Services (ChanServ, NickServ, MemoServ) are designed to possibly eliminate most purposes that bots were originally designed for. ChanServ sets and locks channel modes and topics. It also may automatically op or ban people, depending on their access to the channel.
There are some things which Services can not do, however. A good bot can sometimes protect channels more efficiently than ChanServ. Scripts can be added to bots which kick users for banning, swearing, etc. Other scripts can be added for entertainment, which ChanServ usually does not provide.
The worst use for a bot is to keep a channel open when there is nobody there. These bots are simply a waste of bandwidth, and take up a connection that a live user could be using.
Each server has a different bot policy. While registration of bots is a thing of the past, it is up to each server's admin whether he/she wishes to allow bots on the server or not. Harmful bots are banned from ALL servers.
The best way to see if a server allows bots is to check the MOTD (Message of the Day) of the individual servers in order to verify their Bot Policy. The command to do so is /motd servername.*. Example: /motd twisted.*.
Depending on what type of bot you wish to run, there are several excellent sources. http://www.mircscripts.org is a very popular source for both eggdrop and mIRC scripts. It is suggested that you write your own scripts however, as downloading scripts written by somebody else leaves you vulnerable to backdoors which may cause you to lose your nickname or channel.
Another recommended website is http://www.egghelp.org for eggdrops.
The recommended help channel for bots and scripts is #HelpDesk. #mIRC is the help channel for the mIRC client itself, but script questions will not usually be answered there.
Servers which allow bots will let you run a bot there as long as you want, provided it's not engaged in malicious behavior. If you are approached by an IRC Operator of the server which is running your bot and are asked to remove the bot, please do so.
Absolutely not. Floodbots, clonebots, takeover bots, and other types of war scripts are not allowed on DALnet and will be AKILLed if found.
One bot is enough for anybody, considering most users don't even need that. Multiple bots are considered to be clonebots, and will be removed.