Arrivals
All Irish routes including Northern and Republic of Ireland arrive via Domestic channels as would a normal UK domestic flight would do. This is due to the CTA agreement in place.
Jersey arrives via international arrivals but bypassing border control, as passengers must clear customs.
and of course all other international flights such as from continental EU, USA, Middle East arrive through standard international arrivals, going through immigration/border control and customs.
Regarding CPH - If another airline were to set up for the route, it would be hard for Ryanair or FlyBe to do so since both airports are not Ryanair or FlyBe bases, unless an FR aircraft goes on W pattern from either NCL or CPH. easyJet could easily go on as could BMI (if SVG is dropped or base another A/C).