This can also be translated into English as "I love guitar" without the definite article.
The prompt I got just before this one was "Puni au i ka 'ukulele," which accepted both "I love ukulele" and "I love the ukulele." More consistency on the inclusion of definite articles would be nice.
Is there a way to differentiate classic guitars and electric guitars?
Probably "kika uila"
Is this word order peculiar to this kind of relationship or feeling?
Not particularly. This is standard verb-subject-object syntax of the language.