Hi
Dear
I think IELTS is necessary now.
You can't assess your score without IELTS.
As far as Validity is concerned, I think IELTS shows embassy staff how much comptitent you are not the time period.
1. IELTS is only valid for 1 year for Immigration purposes, as long as you do the IELTS within 1 year of the application submission, it will be accepted..
2. If you are submitting a SAP application, you don't need to the IELTS until requested, if you are doing a full application, then you have to submit IELTS.
PMM