It is likely that, in the
absense of a contract you own the copyright in the photos - if you took them. Your acquaintance (
A) owns the collage aspect of the works only.
It is important to be aware that A may still own copyright in any other works he has created. I note that your question headling "
Who Owns Copyright of WordPress Website and Photos?"
With regards to Wordpress portion of your question: Obviously, A cannot assign the copyright that subsists in Wordpress - something that he doesn't own. However, if he was the original author in other works that he has created for the website such as any page content (text) that he has created, any other graphical elements and any code he has written (CSS, HTML, JSS, etc.) - for plugins, extensions, page layout, etc - then he will likely have exclusive rights to those works as well.
As you have probably already paid him, and therefore consideration has passed, (and as it appears there is no contract) the correct way to assign the rights in copyright that he owns, is with a deed of assignment - A must agree to, and sign this deed. An
intellectual property lawyer will need to prepare the deed to ensure all relevant rights are properly assigned to you, or your company as the case may be.
Hope this helps
Ben