From Shenzhen airport to Hong Kong

Reading about it makes it look a bit like an odyssey.
From the airport by...
then to the customs/border/immigration
cross a bridge on foot once immigration cleared
and then MTR (train) to your chosen destination in HK
Some say it takes 4 hours , others well over 2.
Remember that if you are going into china, you'll need a double entry VISA.

I'll carry on my reseach. I want to make sure i allow plenty of time for this "transfer" because I'll be there during the 1st week of October, China National Day. Millions of people travelling around.

 Right here is first-hand information on how to get to Comfort Home Shenzen.

Taking into account China's quality of accommodation, it was acceptable.
Staff spoke no word of English. Nothing, nada, rien, not a single word. It was awkward, if necessary, use google translator to communicate if you need to, they've got a computer there. There being on a 10th floor of a massive building, just by an open door of what could be / is a flat.  Just follow the directions given on the booking.com website.
My directions:
When you come out of immigration arriving in from Hong Kong, you'll see a massive square/ plaza, go across the whole length of it, go up to street level, towards the shangri-la hotel (big yellow neon signs, you can't miss it) right in front of you. It's overwhelming the first time you see, particularly at night time.

It's past the shangri-la, on your right your should be able to make out a high-rise with a kind oval thing on top.

Go to google , type the name of the hotel and look at the pictures. What really helped me spot the place was having seen the picture. The big oval thing on top of this high-rise was key. Hadn't been this oval thing, i would still be searching for it. No sign of hotel,no name, nothing. Read the comments people make, look at pics and good luck. At night it is hard to find . Within walking distance of metro and immigration, under 10 minutes if you know where you are going.

Plenty of restaurants around, and a massage place we tried.

It must be said that we were approached by people offering rooms for a bit less than what we paid at the comfort home, so I wouldn't worry if you arrive in shenzhen with no accommodation previously booked. Plenty of hotels around of un-tested quality.

Room was big, old fashined and basic with a stinking friedge but roomy and with clean sheets. Ok.

Flights and prices and airlines

We'll be in China during the one-week long holiday period on the 1st week of October. Guidebooks and other travellers say it's not a good idea as hundreds of millions of people travel around and transport and accommodation is hard to find. Advanced bookings are highly recommended apparently!
So almost two months ahead, i find myself pulling my hair at trying to work out how to move around and fix our route, which is nerve-wrecking for someone like me but fun, it's part of the fun!
A colleague recommended using :

www.elong.com for budget flights and accommodation (linked to trip advisor).
they charge 36yuans if you use a foreing (non-chinese) credit card, but it's straight-forward and hassle-free, which is unusual for asian airlines. 
you can also use www.ctrip.com

Used elong so far to book:

Beijing - Shanghai for 460Y + 150Ytax + 36Y foreign credit card tax.
Shanghai - Shenzhen (chinese "side" of Hong Kong): same price

The crowds will be horrible but it'll be interesting to see a holiday in China.
Now we've got to book the flight Guilin area, Changchun and back to Beijing.