Hello,
I'm pleased to advise that WHMCS includes a number of reports which can fill these requirements:

  1. Invoices can be exported between two dates via Reports >PDF Batch
  2. Invoice summaries, including all the information listed can be exported via the Reports > Invoices export report.
  3. A summary of tax liability per invoice by period can be exported via Reports > Sales Tax Liability

All reports are unencoded, so can be customised to meet your specific requirements: https://docs.whmcs.com/Reports#Customising_Reports
And finally; WHMCS doesn't currently have an expense tracking feature, but please do join the discussion for this feature request: https://requests.whmcs.com/topic/expense-balance-feature
Explaining what kind of reporting would be beneficial to you were this feature implemented, is helpful for us to know.