Is this the same as asking where someone is from?
No, you're just asking where their country is located; it's implies that the person already told you where he/she's from and that you suck at geography if you need to ask where that is ;)
Can you say "kien via lando"?
No. You are missing the verb.
I'm guessing grammatical word order here would be quite free. What can move and what can't?
Why "Kie estas la via lando." is incorrect?
"La via lando" is incorrect.
I know this is an old message, but I have only just come across it. "La via" is like "yours" in English. "My country is in Europe. Where is yours?" In Esperanto, that would be: "Mia lando estas en Eûropo. Kie estas la via?"
Directly translated: where is the your country?
If the word ends with -a like "via" does it mean it possessive?
Only if it is a pronoun, other than that they will act like adjectives