Γεια σου Ιάκοβε
1. In Greek when we refer to wine, we prefer the adjective λευκό and not άσπρο. (άσπρο is not wrong, but λευκό is much better).
We can either say “ένα ποτήρι λευκό κρασί” or “ένα ποτήρι κρασί λευκό.”
The first is more common, the second is more emphatic on the “white” property. In Greek we usually put the adjective before the noun. We put it after the noun, when we emphasize on the adjective. The second sentence is like saying “I want white wine, not red.” So both phrases are correct, depending on where we want to emphasize.
About the series of words in a Greek sentence:
Of course there are rules and we cannot put words anywhere. There is much flexibility though, because Greek syntax is more based on the conjugative system (endings of verbs and nouns) and not on the order of words.
“I see you”
In English verbs are not conjugated, so the order of words indicates the subject. (“I”, the word before the verb “see”, is subject.) If we change the order, the meaning changes.
In the phrase “you see”, the subject is "you", because it comes before the verb "see".
In Greek we can say “ βλέπω εσένα” or “εσένα βλέπω”. There is no difference in the meaning, because the subject is indicated by the ending ω of the verb βλέπω and not by the order of words. They both mean “I see you.”
So generally, there are rules for the order of words, but the nature of Greek language allows for flexibility.
2. As for the other part of your question:
We say in Greek “Γεια σας κύριε” or “Γεια σας κυρία” when we address with respect to someone that we don't know his/her name.( for example when a service person addresses a customer.)
If we want to greet a person that we know (ex. a neighbor) it's much better to call him with his/her name. “Γεια σας κύριε Παπαδόπουλε.” Otherwise it sounds a bit as if we don't remember his name or we want to keep him at distance. It is much more polite to greet someone with his name.
In small places (villages), people sometimes greet strangers on the street. You may hear a stranger in a village tell you “καλημέρα”, this is a part of Greek culture. However “Γεια σας κύριε” sounds too respectful, I haven't heard it.