In order for Endnote to generate in-text citations having the author and year format you’ll need to create the citation template as there are no citation templates in the oscola 4th edn style (refer to attached image). Note that the author and year citation will be automatically generated. In cases where you wish just to have the author displayed without the year you can manually the citation to “hide” the year.
It’s unclear how you want the author and year citation to unformatted but as a point of reference you might check endnote’s Author-Date output style’s citation template (refer to attached image). (To edit the Endnote output style file go to the Endnote toolbar and select Edit >Output Styles >Edit [name of your output style].)
As for the cross-citation, if the footnote number is meant to be included as part of an in-text citation you could edit the citation to include the footnote number (and explanatory text) in the suffix field of the Edit Citations dialog box.
