The Perform section cannot perform commands when mIRC starts up, only when you connect to an IRC server.

To perform commands when mIRC starts you do indeed need a script, you need to use the ON START event, see /help ON START. You might use something like this:

ON *:START:{
server irc.server.here -j #channel1,#channel2,#channel3
server -m other.server.here -j #blah,#blah,#blah
server -m another.server.here -j #some,#other,#channels
}

This would connect to 3 servers when you start mIRC and automatically join the specified channels.

For mIRC bots, check out the following websites:

www.mirc.net
www.mircscripts.com
www.hawkee.com
www.mircscripts.org
www.google.com (Search)

Regards,

Mentality/Chris