> indefinite: ormr langr a long worm
> definite: ormrinn langi the long worm
> also definite: Eirikr langi long Eric or Eric the long
>
> Have I got that right?
Yeah, just about. But there are more possibilities:
langr ormr
ormr inn langi
inn langi ormr
And proper names don't always take the definite form.
These are all attested: