Citizenship query

Hi I am due to apply my citizenship.I have some concerns before i apply.Please help me with those queries

I was overstayed 23 days in 2009 due to payment issue.
But it was not my fault as i had letter from the bank stating that there was not any attempt to take miney by UKVI.And i got my ILR last year.I give this letter on my ILR application as well as my other application all have been successful.

1.Now i am applying for citizenship as far as i know that is totaly different law when its come to nationality application.
Do i have to write the cover letter for the reason again

2.can it be refused due to this reason?

3.i am working for the company last 11 years.only i was working for another company as Christmas temp in 2007.but I forgot
Forgot the actual starting date and finishing date of the employment.as i tried with hmrc they only can provide 6 years history.what shiuld i do in this situation.

i will be greatful to you if you can help me with this query