Are strollers practical in Hong Kong?

Only if they are lightweight and compact. Avoid giant American-style joggers; they won't fit on buses or through many shop doors.

Where is the best place to find diapers and baby supplies?

Mannings or Watsons. There is one on almost every city block. Don't overpack supplies.

Navigating Hong Kong Neighborhoods with Kids

Stick to Hong Kong Island's north shore or Tsim Sha Tsui for the best pedestrian access and transport links. Use the MTR and iconic ferries to minimize walking distances for little legs.

Pick a Base. Stay in Central or Admiralty if you want walking access to parks and the Peak Tram, or Tsim Sha Tsui for harbor views and museums. Avoid staying in steep areas like Mid-Levels unless you are prepared to carry strollers up long flights of stairs.
Master the MTR. Every MTR station has elevators, but they aren't always near the main entrance. Look for the 'Lift' signage before descending. Keep a child-specific Octopus card for discounted fares.
Use the Mid-Levels Escalator Wisely. The world's longest outdoor covered escalator is great for getting up the hill toward Soho, but remember it only moves downhill until 10:00 AM. After that, it flips to uphill.
Escape to the Islands. Lamma or Discovery Bay are pedestrian-only zones. Take the ferry from Central Pier 4 or 3 for a car-free day where kids can run around safely.

Are strollers practical in Hong Kong?: Only if they are lightweight and compact. Avoid giant American-style joggers; they won't fit on buses or through many shop doors.
Where is the best place to find diapers and baby supplies?: Mannings or Watsons. There is one on almost every city block. Don't overpack supplies.