General ACCAHelp with PAYE

Hi All, Almost qualified ACCA student here, I have been offered the opportunity to start doing the PAYE for a new company; I would like to take up this opportunity mainly for the experience however there are a few things I am struggling with... I have downloaded the HMRC payroll software which allows me to check the calculations regarding Employer contributions etc so I think that side of things is covered but I would like some advice on the following: 1) The company currently only has one employee who is also the director - Does the director have to have Pension Contributions? 2) How can I accurately select the correct NI letter for this employee (And any future employees), I have read the details on the Gov website however I am not confident that I can make a competent decision. Any help will be greatly received. Thank you in advance, Steph.