Questions & Answers about Bíllinn kostar mikið.
You use the question word hvað (“what/how much”) and follow the V2 word order (verb second):
• Hvað kostar bíllinn?
Literally: What costs the-car?
Yes. Instead of talking about cost, you can state a quality:
• Bíllinn er dýr.
That means “The car is expensive.” Note that kostar mikið focuses on the amount you pay, while er dýr simply calls the car “expensive.”
Drop the definite suffix -inn, giving the indefinite singular:
• Bíll kostar mikið.
Keep in mind that using a bare singular indefinite like this can sound generic or a bit odd in Icelandic; you might instead specify Bíll kostar mikinn pening (“A car costs a lot of money”).
Yes. Fronting the adverb highlights the degree:
• Mikið kostar bíllinn!
This exclaims “Wow, the car costs a lot!” by placing the focus on mikið.