Citizenship Documentations and section 1.1 and section 3.5

I have taken appointment for NCS. Application is for me +my wife + 3 year son (born in India)

My case is as follows WP+ Tier 1+ ILR (total 6 years)

I have following questions regarding documentation and application forms

I have following documents
a. Completed application form AN for me and wife and
MN1 for child with photo of each
b. Passport for all ( my , my wife and child)
c. Life in UK test certificate for me and my wife
d. Marriage Certificate
e. Birth certificate of child

Questions,
1. Do I need to carry council tax bills, utility bills, and employment letters, P60, salary slips other than above documents or above documents is sufficient ?

2. I have following question while completing Form AN

For section 1.1
Please give previous Immigration and Nationality Directorate or Border and
Immigration Agency or UK Border Agency reference numbers
- What should I write here?
There is one number on my passport ILR stamping page (UK......), should i write that number of the number on ILR letter saying (S....).
If I write number on ILR letter saying (S....), then my wife and son doesn’t have these numbers on their ILR letters?

For section 3.5
Address of tax office or tax office reference
- I have gone through some post on immigration board and some has asked to write the ‘Employer PAYEE reference’ which is written on extreme left side of P60.
However I have changed my employer recently.
OR there is UTR number (Unique Tax payer reference number -10 digit reference number) written on some HMRC’s letter to me.
Which number I have to write UTR number OR employer PAYEE reference number OR NI number ?

For Child MN1
Section 1.1

Please indicate the section of the British Nationality Act 1981 under which you
would like the application considered
- Is Section 3 (1), correct answer because my son born in India? .

Questions,
1. Do I need to carry council tax bills, utility bills, and employment letters, P60, salary slips other than above documents or above documents is sufficient ?

No you do not need any of above

2. I have following question while completing Form AN

For section 1.1
Please give previous Immigration and Nationality Directorate or Border and
Immigration Agency or UK Border Agency reference numbers
- What should I write here?

Leave it blank

For section 3.5
Address of tax office or tax office reference
- I have gone through some post on immigration board and some has asked to write the ‘Employer PAYEE reference’ which is written on extreme left side of P60.
However I have changed my employer recently.
OR there is UTR number (Unique Tax payer reference number -10 digit reference number) written on some HMRC’s letter to me.
Which number I have to write UTR number OR employer PAYEE reference number OR NI number ?

Write UTR number OR employer PAYEE reference, your call