1) General Conditions is probably the chapter heading - Clause 4.3, Decennial Liability is under this chapter. There are clauses 1.0...., 2.0..., 3.0...4.0. 4.1, 4.2, 4.3 ....
2) "to" is following "references".- it can be read more clearly as " references to 'errors...' in clause 4.3 of the General Conditions ..."