Hello
Thank you for posting this project
Im expert on PHP/Jquery/Sql, please check my reviews to know more about my skills, profesionalism and honesty
I do have plenty of experience working on APIs integrations thru REST or even SOAP also
I could read the attched document, and is good to have the php code organized as you describe, will sure make the tasks easier
My normal hour rate is between 20/30USD depending on the project and customer
Looking forward to your reply, best regards
Diego