The non-editable records are all related to the services that you've set up for the domain through Dreamhost. For instance, if you've set up the domain or any subdomains for hosting at Dreamhost, the panel will automatically create uneditable DNS records pointing to the proper Dreamhost web server.
If you delete hosting for those domains and subdomains, the DNS records will be deleted and you'll be able to manually add/edit them.
What are [color=#CC0000]50DISK50[/color], [color=#CC0000]3DOM50[/color], and [color=#CC0000]1IP1DOM50[/color]?
They're Dreamhost coupons!