Installing wordpress to run on xampp Lion OS X
If you want to install Wordpress then you can try using AMPPS for Mac, you can install Wordpress very easily on a single click and also get immediate updates, it also provides 230+ scripts with it. I started using AMPPS for my Mac 10.7.1 some days back and I didn't faced any problem till now as it has a very friendly GUI. You can just give it a try.
You probably don't need FTP while working locally. So I wouldn't worry too much about the error there.
Once you have xampp homescreen, that means that you're set up - any websites / applications you write should go inside httpdocs/ folder; so you end up with
httpdocs/.httpdocs/Wordpress
If you go to http://localhost/Wordpress/ you should see the Wordpress installation screen.
That should be enough to get you started :)