Decrypt and Modify Site to check external APi for availability

I need someone to decrypt and modify my site to check external XML/JSON api/db for availability of rental properties and also have a good mix of my sites listings, that does not use the api and deliver results by checking live availability. You will be doing it on a test site and then have to keep track of the files changed and just move them to the real domain. You will have to check for available dates, beds, area, listing types and more.