The area to the east of the viaduct
The photograph must have been taken between the near-completion of the viaduct and the construction of Mt Zion Methodist Chapel, which would have been visible at (1), i.e. about 1907. However, several parts of the image have been re-touched, so perhaps that area has been as well.
At (2) is Tamar Terrace, partially obscuring the Masonic Hall which is the next building uphill.
The Quayside has been embanked and the slipway at 3 no longer exists. Instead a floating pontoon was in use for several decades.