Hi mate,
Which part of Beijing are you in? I'm mainly familiar with Dongzeman / Sanlitun District, I only get to Beijing for a couple of days either side of travelling to and from Manchester, two or three times a year.
I was in Beijing for the 2012 friendly against Arsenal, I don't think that the tickets were available on the OS, I don't know how others got the tickets but if I recall correctly I found the website for the promoters - it had a stadium layout online similar to the City OS Ticketing, I identified where I wanted to be, told my stepdaughter (she's Chinese), she phoned them and an hour or so later a guy on a moped rocked up at the hotel with the tickets, I handed over the cash and that was it.
I'd be interested if you could point out any decent watering holes, the Den has closed down, Paddy O'Shea's is OK but very raggy, even though the Irish rag has sold the place to some French bloke. The only other decent place I know of is the Blue Frog in Sanlitun but it isn't a football kind of place.
I was in Shenzhen around 6 years ago, as you say it's OK but of the two I prefer Beijing myself. There were a couple of reasonable Irish bars in Shenzhen and a decent German bar on a concrete encased ship, there was a night club / disco sort of thing in there but I didn't go in, my missus was suggesting it was some sort of den of iniquity...
Oh yes, Shanghai from Beijing in three hours by train? I don't think so mate, more like 5 hours give or take.
This is a good website for making travel arrangements in China, I've posted the link on other China related threads but here it is again:
https://www.travelchinaguide.com/china-trains/