Hi @Oceanz - welcome!
I have a son with autism, and his abilities and capacity vary depending on the topic. I’ll deal with your topics in reverse order - it’s easier for me!
B. The four criteria you mention are, essentially, true. Capacity is assessed for each decision to be made where there are concerns that capacity is limited or non-existent, and the decision-making process is assessed against those criteria.
With my son, he can be helped to make decisions about some things (shopping needs, for example), but where his obsessions are involved, he’s more likely to follow his obsession than weigh up the pros and cons. Therefore…
A. I suggest you list out what your caree has obsessions about, or particular fears/concerns/anxieties. A few examples (there are no doubt thousands!) might be:
Fear of animals/animal hair - this could affect the person’s ability to engage with a pet owner, for example.
Extreme vulnerability/desperation for social contact or friends - potentially leading to financial or other forms of abuse.
Hygiene obsessions - excessively obsessed with cleanliness, to the point of OCD, or avoidant of contact with water/soap, not changing clothes regularly enough.
Knowing the person you’re caring for will help you to find the “hot spots” - and to look at what would be needed to assess their capacity.
This site is useful: Mental Capacity Act 2005 at a glance - SCIE
This is also useful - it gives details of some free resources: Free resources for the Mental Capacity Act – Mental Capacity Ltd
This workbook is pretty useful as it’s used for training staff. It’s fairly clear and has all the answers for the quiz at the end! MCA-Carer-eBook.pdf
Finally, please make sure you look at this one: What is The Mental Capacity Act? | Mencap Mencap have produced a really useful and clear webpage and links, which show the importance of working with the person being assessed to ensure they are as empowered as possible, rather than the aim of closing down options.
Hope this helps!