What I need you to specify is exactly the information that you currently glean from their /whois, which is helpful to you on your quest.
Their IP/host is automatically disclosed to you when they join the channel, without you having to do anything. mIRC even has the option '[x] Show Addresses' to make them visible to you when they join/part/quit/nick
You say "but it's all I have," allow me be to the judge -- maybe I know something better
Yes, it would be trivial to add bad people and their addresses to a list. You can even add them to your ban list.