Develop an iPhone app that can perform the following tasks, in order of priority:
1. enables our clients to access, view and visualize their agricultural node data.
2. includes a customized calculator to complete frequently needed but simple mathematical computations.
3. allows for the buying/selling of an agricultural commodity.
4. can access via REST or SOAP protocol public weather station data for client view and visualization.
Freelancer must be able to review current MySQL config to determine suitability and perform necessary modifications to support app and website needs. Upon completion of the app, a new project will be launched to update the current website to a responsive design with the same functions and capabilities of the app. Significant server side code exists (in PHP) and every effort must be made to retain as much of this code as possible.