U dont need to do any of that...
Get an SQL backup from the main site that you want to clone from. Change every spot the old domain shows up in the sql, to the new one you are working on..
Get a backup of your wp-content folder as well..
Go to your new site..install wordpress....Go back and upload the sql database over the new one...
Then, overwrite the wp-content folder you just installed with the copy..
From there its minor changes to "fit" that site.
Hope this helps..