A simple PHP Job

I need to fix the attached enhancements in the following site under development [login to view URL] Please review the attached changes carefully before bidding. Please bid only if you can understand all changes. 2 Programmers have already accepted the job and could not complete it. I do not want to repeat the same for the third time. Please tell me which is the most difficult requirement to do in your opinion out of all the requirements. Ajax technology must be used whenever possible. Please read the project first and write the word "Understood". Also write your steps and suggestions to complete the project with a short description of what you understood.