Breakdown of Вы хотите что-нибудь заказать?
вы
you (plural)
хотеть
to want
что-нибудь
anything / something (unspecified)
заказать
to order
Questions & Answers about Вы хотите что-нибудь заказать?
Why does this sentence use что-нибудь instead of что-то?
The suffix -нибудь is used for things that don't exist yet, aren't specific, or when any option will do. In questions like this, you are asking if they want to order "anything at all." If you used что-то (something), it would imply that they have a specific item in mind that they want to order, but you just don't know what it is.
Why is the perfective verb заказать used here instead of the imperfective заказывать?
You are asking if they want to place a single, completed order right now, such as at a restaurant. The perfective заказать focuses on the result of the action (the order being successfully placed). The imperfective заказывать would imply a repeated action or the general, ongoing process of ordering.
What case is что-нибудь in this sentence?
It is in the accusative case because it is the direct object of the verb заказать (to order). Because что (and words built from it) is inanimate, its accusative form looks exactly the same as its nominative form.
Could I put что-нибудь at the very end of the sentence?
Yes, you can. Вы хотите заказать что-нибудь? is completely correct. Russian word order is flexible, but placing a short pronoun like что-нибудь right before the infinitive verb is extremely common and sounds very natural.