Good to see you've been doing some reading.
Do a bit more and you'll see several recent threads discussing stop-overs ...
With 10 hours, you'll have about 7 hours to play - more than enough. Choosing is up to you as it depends entirely on your taste - all we'd say is don't make a shortlist until a few days before coming, and make sure you have alternates for your favourites. Again HG or walkup is a matter of your taste and budget, both are great but HG has a higher chance of getting a glamour girl if you're pushed for time.
Given that your itinerary would be really simple:
go through immigration
straight onto the airport express
get off at Hong Kong station
start calling HGs to find one who's free
walk through Exchange Square, to the Star Ferry, just to be a tourist
go to the girl's hotel
have fun
do your camera shopping, will leave you about 3 hours in hand
take a shuttle bus from TST back to Kowloon Station
Airport Express back to your plane
For the shopping, you'd do well to avoid the string of small shops you'll see on the street in TST. A better way is to go to Harbour City, they have Fortress, Broadway, and a couple of other reputable camera / phone shops all close to each other and competing with each other without ripping people off. Or if you're more adventurous, go to Mong KoK for the full-on Hong Kong Hustle experience.
