Cannot search web site in https://sites.google.com/site/

You may want to consider using the service DropBox instead.

You are really set on Google Sites you create a sub-site with your files set to non public (requires login). yYou have to manually enter who has permissions to view the page however. You can also do page level permissions and select which emails can either view or edit certain pages. You would then upload the Docs you want then link to the doc on the relevant pages

The 3rd option would be to upload them to Google Docs and then enter the email address you want to share the doc with.

Overall, just get a DropBox account.

To be able to reuse a site URL, the original site should be deleted permanently first. To make that this be applied to all the Google Servers could take a while, so wait few hours, better, one or two days.

It's worth to say that Google Sites allow to have multiple owners, so it's not neccessary to delete a site when it was created with the wrong account, instead just add the right account as owner.

From Share your site with other people - Sites Help

Anyone you set to Is owner can change the look and feel of the site as well as make administrative changes, such as deleting the site or adding new owners.