Here is what our tax guy said in reply to this thread as a whole, please let me know if there is a follow question or if he missed something, and I will talk to him again 
- yes - net capital gains for SA108 - we give him the field numbers based on the form https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1063019/sa108-2022.pdf
- yes - other income, SA100 field 17
- he needs to classify everything
Looks like those had been answered though - see #1 above - that is a link to the form SA108 which is what he has to file. If he is using a tool, it will be done through that tool’s UI (similar to turbo tax) otherwise that’s the form and the field numbers correspond to the field numbers in the form
- if the rewards are locked, not income until he actually controls them. here is HMRC’s guidance on staking: CRYPTO21200 - Cryptoassets Manual - HMRC internal manual - GOV.UK - doesn’t address his question, and he won’t find anything addressing that but saying not taxable until unlocked is a very reasonable argument.