Shareholder changes can be notified via a CS01 to show changes that have been made during the period covered by the CSO1. it is NOT a mandatory requirement. If a CS01 is used to notify shareholder changes however, it must do so together with a FULL list of all shareholders.
Shareholder addresses are only required for certain traded companies (not DTR5).
I am not sure off the top of my head regarding the trading issue - I would have to have a think about that.
No the CS01 does not need to include shareholdings - it only allows / caters for changes to shareholders and SIC codes, as and when required, as there is no other statutory way of doing so.