"It is noon, here is the bus."
Translation:Dél van, itt a busz.
Ommitted. "we omit "van" when stating what something is using an adjective or a noun" from http://www.hungarianreference.com/Van-is-exists-omitting.aspx I am not sure how complete this is but it feels ok.
This is because 'Del' comes before the van, because it is the very first subject. The word order: subject-verb-object. The verb: here (itt) would be ''itt a busz'' because that means here is the bus. Because the bus is an object, it's the last thing in your sentence
No, "a busz" is not the object (though an object) but the subject (typically both the subject and object of a sentence are objects :) ). In the stand-alone, "Itt van a busz.", "a busz" is the subject of the sentence, but the "Itt" would be the focus. You know of the bus; the point of the statement is to add to your knowledge of the bus by telling you that it is here. So, here, with the "Dél van" in the first part, we can omit the second "van", but, otherwise, leave the structure is unaffected.
Are you sure that "Dél" is the subject of the first part? If the Hungarian translates literally to "It is noon", then there might be a case for "Van dél", which would be countered by an argument about "Dél" requiring focus, given the assumed existence of this vague "It". On the other hand, should the literal translation of the Hungarian be "Noon is", then "Dél van" would correspond to the subject-verb-object structure.
Because that means "It is noon, it is the bus that is here". Word order is important. When "van" is after "itt" then we know that the emphasis is on the "itt" and then we clarify that the bus has arrived. When "van" is after the "busz" then the emphasis is on the bus, that the bus is there and not something else and the "itt" just clarifies the place.