If I attend a conference in Hong Kong, and stay in the Sheraton Hong Kong, does it have Western style bathroom facilities (seated), or Eastern (squat)?
It depends on the hotel. Upscale ones, especially if they're western brands, will generally have western style (sit) toilets. Cheap hotels, especially if they're local or not a chain, will generally have eastern style (squat) toilets. It's easy to find your preferred style if you know where to look and can identify the clientele the hotel caters to. A large hotel might offer both styles, though I don't know of any that do.
For your specific case, the Sheraton has western style toilets, as you can see from photo #10 in the "rooms" gallery (in the center of the mirror, underneath the flowers, partially obscured by the sink's reflection):
I have not stayed at the Sheraton specifically but based on my experience with other Hong Kong hotels/venues, I am pretty sure you will find “Western” bathrooms there.
But as far as (men's) toilet experience is concerned, in Hong Kong you must try The Peninsula, more specifically its bar (you can go there even if you can't afford the hotel).
The Sheraton is above my discretionary accommodation level - but based on what is provided at less salubrious establishments, I'd expect western toilets in en suites and just maybe a squat toilet or too in shared facilities - usually well labelled on the door.
Even quite down-market Hong-Kong hotels are liable to have western-style toilets in en-suites. As above, in shared wash-rooms with multiple toilets one or a few may be squat style.
I use single 'room with ensuite in hostel' when possible (camera gear and PC safe, OK bed, air-conditioning, internet - what else do you need? :-) ) and these essentially always have western style toilets.
Cross the border into Shenzhen and 'your mileage may vary', with upper level hotels offering flush toilets but lower price accommodation being more likely to provide only a squatty.
Of course it has. All mid to upscale Hotel in China do these days especially if they are name brand. Same for restaurants. The only "hole in the ground" style toilets I've seen in the last 5 years are either in very rural areas or inside the factory for operators and line workers.
Assuming you mean the Sheraton in Kowloon close to the harbor, it's really nice, if a bit dated, hotel. Haven't been there in a while but it used to have a great roof top pool with wonderful views of Victoria Harbor and Hong Kong proper. There also used to be a bar in the basement level that had beer taps build into the walls at the table with meters (like a gas station). When you sit down, they zero out the meter, bring you empty glasses and off you go (if you are into this sort of thing)