No, you don't, you can buy a license to use the photo on one website (blogger) or on one project (extended)

You find more info here.

After you purchased your licenses you'll receive a link to download the photo's without the watermark and in the format according the license bought.

Yes, you can as long as the photo isn't used, licensed to other buyers.
You'll find that buying option if available. 
After you bought exclusive use, the image will be removed from the front end.

If you haven't downloaded your licensed image yet you can but otherwise it's not possible.
Although when there's an error with exclusive use you're entitled to a full refund.
Please contact me for further information.