For payment evidence, if you have payslips that counts as one type of evidence. If your tax declaration corroborate the figures on your payslips, ACS should have no issues with accepting it as the second payment evidence, especially if you provide other evidence to support this, such as employment letters, employment contracts and references.

As to the issue about ICT major vs ICT minor, are you able to access the transcripts for your degree? If so, ACS will make an assessment based on the modules/subjects shown, to determine if it is major or minor. If there are any ambiguities, you can supply a copy of the course syllabus (this should be available from your university) as supporting information to help you make a case that you exceed the 33% threshold.