DNS changes takes quite some time to resolve. You have got to wait a while.
Also when I was working with the Cobalts ( Original RaQ 4 and Original 550 ) I realised that I constantly forget to hit the SAVE button.
Are you using RaQ4 or RaQ550 or as your ID suggest... the RaQ3 GUI? ( You you really are using the RaQ3 GUI, its time to change it to at least a RaQ4 GUI )
Try it out, if it does not work, try using CentOS and Directadmin. I got a tutorial on how you can do that and also juice up your cobalt to run larger than the normal 127GB HDDs
Perhaps I do not understnad your issue. If a "parked" domain is one with simply a default page (in this case, the default Cobalt page), then all one needs to do is create the domain. In the 550/Rackstar interface, there is a checkbox "create DNS records" or some such), and you're done. Other than typing the domain name, it's about 5 mouse clicks. To create the admin user, go to site management and "create user". I don't see how it could be simpler. You still have to tell your upstream registrar to point to the site or its DNS servers.
If by "parking" you do not mean the default Cobalt/Rackstar/whatever page, then simply go to (with ssh/telnet, logged in) /home/sites/<domain>/web and replace index.html with whatever redirect page or "parking" page you want.
If you want the DNS stuff at your upstream registrar done for you --- well, no one does that -- you have to log in and do it.
Honestly, the Cobalt interface is not the most stylish, nor does it contain a double-ton of features for controlling secondary things, but in terms of creating websites, it is hard to see how much simpler it could get.