Once documents are included in the replies to notice for particulars does this mean that they now become evidence and are admissable to the proceedings at all stages?
The other side is entitled as of right to inspection of any document referred to in pleadings (which includes replies to particulars).
Whether a document is evidence as to the contents depends on whether it is an exception to the hearsay rule. The document itself though is evidence that those facts were recorded on the document in question at a certain point in time.