For purpse of registration us 12A of I T Act what is required is
1) Application for registation us 12A [available on site incometaxindia.gov.in] in duplicte to be filed before concern CIT/DIT [exemption]
2) Copy of Registered trust deed or registered society along with by laws
3) Detail name and address of Two trustees
4) Brief history and activity of NGO
As per law within180days from date of filing application CIT / DIT(E) will grant you registrtion us 12A of IT Act . If any further clarification or document is required by CIT/DIT then period required for clarification or furnishingdocument is to be excluded from period of 180 days .
If your appliacation is rejected on ground of clarification or for non production of documents then you can apply afresh by submiting fresh set of application and all documents .
Once you apply for registration us 12A then either simulteneously or seperately you can apply in duplicate before CIT/DIT for exemption us 80G of IT Act
Last Three years P & L A/C and Balance sheets if trust is already working/ functioning alond with auditors report