About the "qu-" pronunciation: that just brought to me my mind some ancient Greek transcription of the Latin name "Quintus" that a friend made a picture of in Greece recently: https://twitter.com/Rodericus/status/642764588111536128
It was transcribed as ΚΥΙΝΤΟΣ and due to the probable age of the transcription there is no reason to think that upsilon would stand there simply instead of some "u" (you could still write "ΚΟΥΙΝΤΟΣ" e.g.) or unlikely for a Greek "yi" diphthong and given also the excerpt from Allen's Vox Latina which is in the next picture in the given link it supports more what we think about the pronunciation qu-.
qua-, que-, qui-, quo-, quu- are either all pronounced as labiovelar stops - that is [kʷ] which should differ from English (quick) or Italian (quanto) [kw] by the simultaneity of the articulations (in the first case they are simultaneous, in the second case they are successive: in the case of kʷ you both round your lips and pronounce k in the same time, not one after another). This has very probably some implications for the quality of the unrounded vowels. (Rounded vowels are those that are articulated not just by the tongue position but also by the lips being rounded: that is usually in our orthographies "o,u" (unless in American English where "o" as in "rock" is unrounded and therefore is closer to what we often perceive as "a"; as in "star" in both American & British pronunciations; but "o" in "more" is rounded even in the American one) ) So "a, e, i" are typically unrounded, but in this case, after -qu, they come close as rounded and sound then similar to [ɒ̈], [œ], [ʏ].
OR (and this is the way I commonly use it):
que-, qui- (unlike the rest of them, which should be pronounced as just described) - before the front vowels, are pronounced not with labialization but palatalization (that is a kind of (semi) consonantal "i"), that is as [kʲ] or [kᶣ] (similar to what French does with "n" in "nuit" [nɥi] ) - that you basically pronounce something between "k" and "j" or a kind of "k" and a very weak "j" between that and the vowel. Then the "i" and "e" will sound basically the same as they sound elsewhere and won't be rounded.
Also quu- is the only case we know about (transcribed as [kʷʊ] ) which will be pronounced quite probably EXACTLY the same as [kʊ] (ku/cu), because the vowel is already rounded and on its own creates a kind of labiovelar allophone (=variant) from the preceding "k" in any language. So we think that all quu- in the classical Latin are just etymological in the orthography and phonetically don't exist anymore. That is equus = ecus (the pronunciations should be THE SAME). If you ask for what reason then there's "equus"in the classical Latin: well, this orthographic irregularity must have come about probably from a desire to keep the declension uniform in writing, that is instead of "ecus, equī, equōrum, ecum, eque..." rather "equus, equī, equōrum, equum, eque...". This is one case where we are quite certain that Romans didn't exactly spoke as they wrote (well in this case: that they wrote more than necessary). (Or antīquus = antīcus).
But almost anytime the reason why to retain "quu-" in writing wasn't justified by more forms in its declension, Romans actually would start to write "ku" (cu): when "quom" turned into "quum" (as servom to servum), you very quickly got "cum" (which was the same pronunciation-wise to quum).
By this logic also quo- should be the same as ko/co, but it doesn't seem so. I'm unable to say why, but it seems there still was some phonetic difference between these two (maybe quo- came as more rounded than ko- / co- would).
Nevertheless, if you speak just about the syllable length where qu- is present, then indeed, as noted by Laurentius, "qu-" is much closer to a simple "k-" than to anything else (e.g. than to kw) and that is the reason why in scansion it is never understood as two consonants.
Most Latinists using the restored pronunciation subscribe to this model in theory, but they rarely do it in practice and simply pronounce a kind of [kw], as we do in English or Italian. It is surely because there seems to be almost none widely known language that would use the sound and therefore we have not much to imitate. So, if you are not sure how to pronounce it, you shouldn't give up on the restored pronunciation but still can use the compromise [kw].
It was transcribed as ΚΥΙΝΤΟΣ and due to the probable age of the transcription there is no reason to think that upsilon would stand there simply instead of some "u" (you could still write "ΚΟΥΙΝΤΟΣ" e.g.) or unlikely for a Greek "yi" diphthong and given also the excerpt from Allen's Vox Latina which is in the next picture in the given link it supports more what we think about the pronunciation qu-.
qua-, que-, qui-, quo-, quu- are either all pronounced as labiovelar stops - that is [kʷ] which should differ from English (quick) or Italian (quanto) [kw] by the simultaneity of the articulations (in the first case they are simultaneous, in the second case they are successive: in the case of kʷ you both round your lips and pronounce k in the same time, not one after another). This has very probably some implications for the quality of the unrounded vowels. (Rounded vowels are those that are articulated not just by the tongue position but also by the lips being rounded: that is usually in our orthographies "o,u" (unless in American English where "o" as in "rock" is unrounded and therefore is closer to what we often perceive as "a"; as in "star" in both American & British pronunciations; but "o" in "more" is rounded even in the American one) ) So "a, e, i" are typically unrounded, but in this case, after -qu, they come close as rounded and sound then similar to [ɒ̈], [œ], [ʏ].
OR (and this is the way I commonly use it):
que-, qui- (unlike the rest of them, which should be pronounced as just described) - before the front vowels, are pronounced not with labialization but palatalization (that is a kind of (semi) consonantal "i"), that is as [kʲ] or [kᶣ] (similar to what French does with "n" in "nuit" [nɥi] ) - that you basically pronounce something between "k" and "j" or a kind of "k" and a very weak "j" between that and the vowel. Then the "i" and "e" will sound basically the same as they sound elsewhere and won't be rounded.
Also quu- is the only case we know about (transcribed as [kʷʊ] ) which will be pronounced quite probably EXACTLY the same as [kʊ] (ku/cu), because the vowel is already rounded and on its own creates a kind of labiovelar allophone (=variant) from the preceding "k" in any language. So we think that all quu- in the classical Latin are just etymological in the orthography and phonetically don't exist anymore. That is equus = ecus (the pronunciations should be THE SAME). If you ask for what reason then there's "equus"in the classical Latin: well, this orthographic irregularity must have come about probably from a desire to keep the declension uniform in writing, that is instead of "ecus, equī, equōrum, ecum, eque..." rather "equus, equī, equōrum, equum, eque...". This is one case where we are quite certain that Romans didn't exactly spoke as they wrote (well in this case: that they wrote more than necessary). (Or antīquus = antīcus).
But almost anytime the reason why to retain "quu-" in writing wasn't justified by more forms in its declension, Romans actually would start to write "ku" (cu): when "quom" turned into "quum" (as servom to servum), you very quickly got "cum" (which was the same pronunciation-wise to quum).
By this logic also quo- should be the same as ko/co, but it doesn't seem so. I'm unable to say why, but it seems there still was some phonetic difference between these two (maybe quo- came as more rounded than ko- / co- would).
Nevertheless, if you speak just about the syllable length where qu- is present, then indeed, as noted by Laurentius, "qu-" is much closer to a simple "k-" than to anything else (e.g. than to kw) and that is the reason why in scansion it is never understood as two consonants.
Most Latinists using the restored pronunciation subscribe to this model in theory, but they rarely do it in practice and simply pronounce a kind of [kw], as we do in English or Italian. It is surely because there seems to be almost none widely known language that would use the sound and therefore we have not much to imitate. So, if you are not sure how to pronounce it, you shouldn't give up on the restored pronunciation but still can use the compromise [kw].
