With "range of colours" (or colors) "is" outnumbers "are" on ngrams by 5:1.

I would regard "a pair of", a number of, a couple of - like "lots of" as being so common as to have achieved a status similar to determiners such as much/many/these/those/some/any

My first question would be: English has changed a bit since William the Bastard and his mates landed in 1066 to undertake a social redevelopment program; under what circumstances is it okay to make changes now?

Google Books ngram suggests that:
"crowd was on its feet" outnumbers the rest by at least 5:1, by far the commonest;
"crowd was on their feet" in US books is next,
and the rest are also-rans - right or wrong, they are comparatively uncommon.

synecdoche - totum pro parte - or sometimes pure ellipsis of the word "members".

@HS I would not doubt your own recollections: frankly what happened to me in those far off days is still clear as a bell - tolling over a fleld in Austria with black-clad peasants scything the wheaten harvest in '63 - whereas well where did I park the car?? But I digress..
My experience is that there was a seismic social shift in the early sixties and English people just a few years older then me are quite nice enough but have a totally different mindset. There is sometimes a gulf of non-understanding between the last of the 'silent generation' and the baby-boomers.
That aside, I teach "people are..", "the police are..", "the staff are .. " to ESOL students and let it go at that. And I'm okay with "the team are disgruntled" or "the team is disgruntled", although I recognize that one or other may well sound "wrong" to some people (depending on which side of the Atlantic or whatever).
These days there is little that is "right" or "wrong", as some politicians at home and abroad have amply demonstrated. I'm pretty certain St Peter himself, who is still swotting up on English grammar and will be for some time, won't hold it against us.

@HS It is indeed very hard to escape the outlook that was embedded by our schooling; although by the standards of the time I myself was very fortunate indeed and has some of the very best available. (Though of course nothing is magic).
I do recognize that somehow where I grew up the pre-1960's people didn't seem to question everything in the same way as us baby-boomers did; I well remember the deputy principal describing my views as "iconoclastic" ( I was reading "So Sprach Zarathustra" at the time). I think over the last ten years "Western" education has changed again, as so much material "knowledge" is just a click away on the web.
That said I think I learnt more about life from blundering round Europe and finding out to soon that with a little help from a friend one plus one can all to easily make three.
I am not quite clear on where you went to school but will ask a friend who went to Rosmini about collective nouns and singular verbs at the hands of the Brothers.

@HS Good - it's all about what criteria we are using.
By the way, "if it sounds strange" - to whom? To you, to me or to 5000 Man C fans?

@HS Those "harried souls" must be proud to see you have your own well-founded views despite (!) their teachings. Perhaps the real question is why did those "harried souls" teach that collective nouns must take a singular verb? Whence came this wisdom of the ancients?
Although to be fair I cannot imagine either of us standing up in class and asking:
"Please Sir, where did you get all this bollocks from Sir?"

"At school I was taught ....." (HS)

One should not believe everything one is taught at school. Knowing what is worth knowing and what is bollocks is all that matters.

“My education was interrupted only by my schooling” - Winston

"Schools have not necessarily much to do with education...they are mainly institutions of control where certain basic habits must be inculcated in the young. Education is quite different and has little place in school." ~ Winston Churchill

So that makes it all pretty easy; all one needs is a sound knowledge of the GVS, a smaltering of Latin-ing, a soupcon of medaeval French and Bob is indeed to goodness your uncle. It is but a small "en-devoir" or endeavour or endeavor or whatever.
However sins enii olternativ speling sistem wud luk vaastlii diferent and distroi backwerds kompatibiliti chaenjing wud not bii werth it.