One way of expressing surprise is to add the word nam to a question, which seems to add a sense of "... and I really have no idea what the answer is". Lewis and Short (section III of the entry) describe this use of nam as "expressing wonder or emotion in the questioner". Nam often follows the interrogative pronoun quis and is written together as one word, ...
I found an article that gives some excellent examples of this usage as well as practical tips for how to recognize it: Thomas Nelson, "The Third Qui, and Six Ways to Recognize It, or 'Who Happens, Maecenas?'"
Nelson begins by noting that there are three kinds of qui. The first two are ubiquitous, and found in the L&S entry for the first meaning of qui:
It's often difficult to match idioms exactly between languages, but in at least one case you mention Latin has an almost exact equivalent: Ubi terrarum...?
non edepol nunc ubi terrarum sim scio (Plautus, Amphitruo 336)
Now I don't have a clue where on earth I am.
Quid istúc est? aut ubi istúc est terrarum loci? (Plautus, Asinaria 32)
What is this?...
I read the second half of the passage like so:
utrum omnes quasi occiderint teneantur videamus
videamus, utrum omnes teneantur quasi [servum] occiderint
"let us see, whether everyone should be held as if they killed the slave"
"we will consider whether everyone is liable for killing him"
This is somewhere between the two translations ...
Your idea is correct.
Lewis-Short is not terribly clear:
added in a direct question, as an interrogation mark, to the first or principal word of the clause
but, if you know German, Georges is much clearer: ‑n(e) is attached to the focus of the question, therefore mostly at the beginning of the sentence.
To answer your question completely, a ...
The first thing to note is that the cu- and quo- spellings are equivalent: quoius is an earlier form of cuius, in both the functions you describe. I think your question is really about the relationship between:
the gen. sg. of the relative pronoun, written quoius in Old Latin but cuius in Classical Latin; and
the possessive adjective meaning 'whose', ...
'For how long' can be rendered quamdiu (or quam diu). In this case, because an ongoing state is described, I'd use a present tense verb. For the answer, the accusative of duration does indeed exist in Latin and will work just fine here:
quam diu canis es? quartum quintumve* iam annum canis sum.
* According to Gildersleeve and Lodge (§336), 'In giving ...
I would try to find something that a Roman might have used, and think you would get a more satisfying translation by re-phrasing the English to suggest what words I should use.
Vox for 'word' is legitimate, but a little too fancy for my taste in this situation; and isn't hortor, meaning 'urge strongly', a pretty strong word for 'suggest'? There are ...
I think your last sentence is grammatically correct. The general question is whether it's possible to raise an interrogative out of an ut clause, and there are examples of this:
Quid vis ut curem? (Plautus)
Quid vis ut faciam? (Vulgate)
Quid iubes ut faciam, domina? (Patrologia Latina)
Probably more classical examples could be found, but this is a ...
To answer your second question (since brianpck has already given an excellent answer to the first), quī is etymologically an ablative. The paradigm of the interrogatives quī, quis is a bit odd in that it combines third-declension forms (quis, quem) and first-/second-declension ones (quā, quō). This quī is originally a third-declension ablative form ("by ...
If you want a noun for this purpose, I suggest sententia.
It means things like thought, judgement, opinion, decision, and wish.
You could just ask "sententiae?" or maybe add a verb and go "habe(ti)sne sententias?" to stay close to the English original.
Whether you should use the nominative sententiae or the accusative sententias in the standalone option ...
I suggest that you take a look at this old question about similar structures.
The conclusion was that present tense is the way to go.
Latin has an adverb diu, meaning roughly "for a long time".
I would ask "how long?" as quam diu? instead of using the word tempus.
If you do use tempus, remember that it's a neuter (not quantus tempus).
Lengths of time are ...
Jeanne Marie Neumann, in Lingua Latina: A College Companion, suggests
You will sometimes find quis (i.e. the form of the interrogative pronoun) used instead of quī (the form of the interrogative adjective) before a noun in questions of identity: Quis servus? Medus. [emphasis mine]
In a previous answer, @fvogel offered these examples, all of which meet ...
Wait for someone expert to give you an expert answer, but as someone whose Latin dates from the last millennium I’d say that both utrum and the subjunctive would push me towards an interrogative interpretation. There certainly ought to be a sense of “whether” in there somewhere. Not necessarily going as far as Hulot and putting an explicit question mark.
When in doubt translate literally: "....whether (utrum; would normally expect "necne" = "whether-or-not") we may consider (videamus) as if (quasi) all (omnes) are to be included (teneantur: alt: are-to-be-held [responsible])--they definitely killed (him)."
This strikes me as an indirect question; if so, that explains why it is not completed with a question-...
Typically the direction of movement is expressed with accusative (perhaps with in or ad).
While quo is originally an ablative of the interrogative pronoun, it should not be treated as an ablative here.
Instead, just take it as an adverb, not as an inflected pronoun.
It would be interesting to know why the ablative form evolved into this pronoun.