That article is very old and I should remove it. In later firmware rev's we made it much easier to disable telnet/SSH. Via the web is located here:
System admin-> Security profile-> System security
1. You cannot access the command window from the web UI. You must directly login to the command line via telnet/SSH/CM console port.
2. Yes. You can reset everything except IP, or sections of configuration. That is located here:
System admin-> Config management-> Config import
From there you select "Factory default" for location.
Then under "Config selection" check "Select all". This will select all options except "Including IP config" so that your IP, Gateway, sub mask will not be defaulted.
Then select "Import".
3. See my reply to #1.