Hey, I stayed in Hong Kong for a couple of years before I came to Japan.
I wouldn't bother living in Kwun Tong, as there isn't too much to see or do there. You can have a lot of flexibility where you live, because Hong Kong is small and the transport systems (buses and trains) are superb.
The MTR is better than the Tokyo underground, and the number of buses dwarf the number in Tokyo. Additionally taxi's are everywhere and very cheap (under quarter of the Tokyo price - minimum charge only 200 yen and increments of about 20 yen).
I would recommend you stay in a furnished apartment for the first month, and use the time to explore and find an area you like. Personally I lived in Wan Chai as it was close to work for me, had great restaurants and near Causeway Bay which is a big shopping and entertainment district (think Shinjuku or Shibuya).
Practical things - don't ship electrical appliances as HK uses 220v and replacing things is cheap... everything costs a lot less than it does here. You can eat out for 200-300 yen in the evenings, and have a reasonable meal for 1,000 yen.
Practical things - as mentioned get an Octopus charge and keep it topped up as it's much faster and better than using coins. Even better, you can have it auto-top from your credit card if you apply (any MTR station).
Hong Kong is a great place to live - good luck and enjoy !