First off, I would recommend upgrading to the current version of mIRC, which is 6.35
You can do that by
following this link.Secondly, for your first query, you already have a start using the ON TEXT and ON ACTION events. What you need to add is a comparison to see if the $nick matches the nick that is allowed for the alternative commands/responses.
Lastly (at this point), your second query can be handled the easiest by referring you to sites like
Hawkee and have you search the snippets section for a bad word script.
I know there are a few there, but if you don't like any of them (and don't be afraid to try different wording in the search), you can also try sites like
mirc.net or
mIRC Scripts.org