How long have you lived in the UK section 7.11 - Confused

[satmvv]

I was on student visa for 4 years before getting WP stamped on Jan 28th 2008. I have held the WP for nearly 5 years and have an appointment for ILR on 9th Jan. Please can someone confirm what to mention in the section 7.11 of the new set O form?

Is it 4 years and 11 months (completed) ? or 8 years and 11 months?

Also, cant understand why it asks for periods of absence of more than 6 months, shouldn't one expected to reveal all absences in section 6.2 anyway? Unless the period they are referring to from the very beginning of my entry into UK (with student visa)

Would be grateful if anyone can clarify.