score:3
I know that, due to an internal directive, Shenzhen routinely refuses visas on arrival at the land border from Hong Kong to holders of passport stamps/visas from countries whose citizens are ineligible for this visa on arrival.
To my knowledge, there's no such restriction for air TWOV (including the 144-hour one).
1) What I want to know is, who are the people providing these permits? The immigration officers or a different counter from where I collect some pass and try clearing the immigration later?
It's immigration, but there are specific lanes for it. Check the signs.
2) If I am refused the permit at some desk which is not immigration desk, do I need to declare in future that I was refused entry into Mainland China?
Since you have a connecting ticket allowing you to stay in the transit area for less than 24 hours, they won't have to detain and remove you to your point of origin, i.e. they shouldn't process you as an entry refusal, but simply tell you to remain in the transit zone (make sure to show them your connecting boarding pass in case it happens, so they know the deal)
3) If I get my permit from the desk and proceed towards immigration, and the immigration officers deny me entry, will they put any sort of stamp on my passport?
You get the permit at immigration.
Upvote:2
Just adding my experience as you already have a pretty good answer. I entered China on a 24h TWOV in February 2019 with a Polish passport and no previous travel to the country. I travelled on Air China, arriving from London around 12pm and my onwards flight to Singapore was leaving that same evening.
My only mildly controversial stamp was a weekend in Istanbul, travelling in & out IST airport. I handed in my passport with a completed form and onwards boarding pass and no one asked me any questions or looked at me twice at neither the visa counter or inbound/outbound immigration. From what I've seen in the line, it's mostly Brits/Europeans and Australians queued up and applying for these, and the only ones asked any questions are ones applying for a 144 hours visa to stay for a few days (proof of hotel booking etc).
It's worthwhile to mention that coming back (arriving from Singapore and departing to London later the same day), my inbound flight into Beijing was delayed and when approaching the visa counter, the man said it's too little time (around 7.5h at this point) and I was unable to convince him. From what I've read online there is no magic number (seemingly around 8h minimum) so just be mindful that your plans can be ruined by a 1.5h delay.