Hi,
Question 1 you can choose either cash basis or traditional accounting if your turnover is under £150000.
Question 2, Cash basis is used when you invoice somebody and received the income in the same tax year. Normally with rental income people claim cash basis because under the rental agreement they pay within the same tax year. Therefore if you received a payment on 10 April 2023. This would be entered in your 2023 to 2024 tax year and not 2022 to 2023.
Question 3, may now be irrelevant but if you did want to claim traditional accounting you would need to apportion yes. Cash Basis no.
Guidance below:
PIM1092 - Cash basis for landlords
Thank you