importing a library and retaining its formatting

nope  – the .ens is a file that tells endnote how to export files from endnote – it doesn’t have any data in it?  

enl files are pointers to data in the library

the library info is all included in .DATA folder with folders in it.  

you can compress a library into a .enlx file which has everything and can be unpacked by endnote into the .enl file and the .DATA folder and contents.  

the ref type table will end in .xml  - instructions are in the preferences – edit>preferences>Reference Types (see attached image) you export and import them there.