For source code and customization go here, http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/80649c2f-3bfc-3010-0da6-ae101dceafea?QuickLink=index&…
The simple 3 documents that I have used to know about FIORI is here, might help you
http://help.sap.com/saphelp_fiori/fiori10_install_en.pdf
http://help.sap.com/saphelp_fiori/fiori10_extend_en.pdf
http://help.sap.com/saphelp_fiori/fiori10_security_en.pdf
As I mentioned before its possible to create apps like fiori but I don't think you can add those apps along with SAP's FIORI set. If you can add in the sap app store same as SAP do.
- Midhun VP