Hi debslosjoe
You can type up your answers and add them as additional pages, but it is not necessary to type up the whole form - just make sure the questions are clearly marked. Make sure you submit the form with your signature on it.
You ask - 'what is the best evidence to use?" There is no 'best evidence'. Claimants submit what they have. If you have letters from a medical professional, that can help. Letters from a family member or friend can help. Some people keep a diary and submit that. Clearly what you write on your form is important. Look at the guid to PIP claims and reviews for guidance on how to answer the questsion
benefitsandwork.co.uk/guides-for-claimants/pip BIS