Most of that stuff you've listed is already built into mIRC:
a "channel box" to join rooms at the click of a button
Channels Folder - 3rd icon from the left on the toolbar.
List Channels Window - Created by using the 4th icon from the left in the toolbar.
a "MODEs box" to set room modes
Channel Central - setup as default double-click action in channel windows, also on channel window popup.
an "OP's box" to set user modes
I'm pretty sure the default listbox popups contain the standard mode changes available to channel ops.
and lastly an "OPER box" to do things like OP-up if you have
Oper modes and abilities vary depending on what modes are set on that person and the IRCd being used. It's not possible for mIRC to have something that will work properly on all the major IRCds available.
Why would an extra readme file or bold text be more effective than the popup warnings available, the warnings in the helpfile about various aspects of security, the media coverage on internet security, or good old common sense?