would caterham parts like cycle wings (front and rear), nose cone, and aeroscreen fit a locost??

Yes because you make your Locost to fit them !

The guards would depend on your tyre size.

The aeroscreen should be able to be adapted (assuming you already have a chassis), provided it is roughly the right width.

The nosecone might be too wide for a 'book' locost, though.

Caterham , nosecone and arches work on a Locost book chassis .

It's sometimes surprising if you ring Caterhams the parts are cheaper than Kitcar copyists , better quality , better service.

And no I do not have shares in caterham cars!!