Hello baloti1,
Primera cams definately will not fit a micra (the engines are different types).
I believe it's possible to fit some types of UK-spec primera injectors into the Micra's fuel rail. However, if won't provide any advantage (in fact the car will probably run worse) unless you also perform other serious modifications at the same time. You would only really need to install larger injectors if you are building a full race engine and/or installing a turbo.