Hi Tillieg
Have a look at the Guide to PIP claims and reviews -
benefitsandwork.co.uk/guides-for-claimants/pip. There is information about the questions he could be asked from page 124. It is not a given they will ask every question. Also, your partner should be aware that they often throw in a 'curveball,' ie a question that is unexpected, and you have no idea why they have asked it. If it happens, tell him not to hurry to answer. Have a drink of water, take a deep breath, ask them to repeat the question - anything that gives him a few moments to think.
We also advise that people should record their assessments even if they have asked the assessor to record it. If your partner decides to record - he should do it covertly. It's your home, so he's free to do as he wishes. However, if you ask the assessor - they may refuse to go ahead with the assessment.
BIS