Cross Platform App UI and Design with backend Content Manager

I'm in need of a cross platform (apple/android) app front and back-end design for two functions, and a linked web CMS.

1. A briefing document that has several questions that are checked and then digitally signed.
2. A document with questions that require a picture to be attached. Door 1 = Picture, Door 2 = Picture etc.

The back end needs to be a web database that can be accessed by store the questions and photographs and store them for 90-days and then self-archive purge. If there is ever a question that a briefing or picture was/wasn't taken, an admin can access the CMS and search the site to find the data.