simple caution or warning

Hi,

I had an argument with my wife in May 2015 and she phoned police and they arrested me. There was no caution/conviction, but they have taken my finger prints in police station and recorded my voice also during enquiry. I came back to home after 2 hours and there was no caution. I also applied for subject access request to check the status and it was mentioned in report that I was arrested on common assault and no further action (NFA).

Now i am planning to apply for citizenship next month and i want to mention my arrest details in form. So my question is, do I need to say YES for 3.5 (have you received any caution (simple caution)... and mention the arrest details?? But I am not sure whether it is a caution in my case?

If I say No for 3.5 then where I need to mention arrest details? Do I need to say NO for 3.5 and write cover letter and mention the arrest details??

And my last question is, it is now 2.5 years, so is there any specific period 2 years or 3 years so that they will not consider this arrest??

Thank you,
Suri

Could any experienced persons reply to my queries please? Thank you in advance..