Had the following documents:
- application form (we used this one, http://www.china-embassy.org/eng/visas/fd/, allows to fill in the pdf and print it. Disable Javascript to put in non-US phone numbers ...). They also had free copies and pens, glue etc at the embassy.
- passport copies, also copy of mongolian entry stamp
- copy of previous chinese visa from earlier this year, as it was in our old passports.
- passport photos
- detailed itinerary for 28 days Beijing to Hong Kong, plus another 2 weeks Hong Kong to somewhere, with stuff to do each day and the place we are staying
- booking.com confirmation for all those hotel bookings
- plane ticket in and out (nothing for HK, as we would obviously go over land). Just did a screenshot of the confirmation before payment, cut nicely so you'd see our names, price/tax, flight details but not the "please pay now" part.
- Nothing else. They also didn't bother about any previous travels, as we had just switched to a new passport and Mongolia were our first entry stamps

Asked for double entry 2x30 days, six months validity, and got it. They actually asked "60 days?", but since our itinerary was only for 30 each entry and a longer stay would not have been of any use to us this time, we said 30 would be fine but please within 6 months, as we had heard stories people had gotten "irregular" visas there before even though 6 months should be standard for double entry ...
Asked about express processing but were told this is not possible for us Germans. Four working days, Wednesday morning to Monday afternoon then, remember they are just open three times a week. It is $30 for single and $60 for double entry payable at a nearby bank whenever you like, just bring the confirmation slip when you pick up your visa. You can pay with MNT, they'll just convert to USD first - as in most places in Mongolia the exchange rate is less than 0,5% off so that's not costing you extra either.
We heard of several others who had gotten the Chinese Visa without problems as well, except for one person, but she had overstayed her last two visas on her trip so that may have been the reason ... so I'd say everything back to normal!