Analysis of Multiple Spreadsheets with multiple tabs for Common and Variable Criteria and Validation

I have 17 t=years of monthly reports , which share the same tabs throughout I need queries run to answer questions I will provide.. Sample questions are > What is the change month to month and does it reconcile with whats reported What are the sums and counts of specific fields in the report, What line items are repeated more than once in specific reports and other analysis you could recomend, i am looking to validate and or find specific errors in the reports month to month These are securutiea investor reports