Teaching English in Hong Kong is a possibility yet it's not that easy to get a job. Hong Kong used to be a British colony so many of the people here speak English. So English teaching is not really in demand compared to nearby countries like mainland China, Taiwan, Korea and Japan.
It's a big city that is densely populated. It's also busy and it suffers from air pollution. But even though it's that big it's pretty easy to get away here to a quiet beach or mountainside that is nearby. Lamma island is really nice and it's just a boat ride away. Lantau island is even bigger than that. Both offer some nice beaches and mountains for hiking.
After a year in Taiwan I came here looking for a teaching gig, but I didn't really find much and I went back to Taiwan. If you time it right you can find a job working as a public school teacher with the NET program. You'll need good qualifications for that and experience. I have occasionally seen jobs teaching in kindergartens or in private schools advertised on Dave's ESL Cafe.
Rent is pretty pricey here. One of the cheapest places to stay in Hong Kong is at Mirador or Chung King Mansions over in Tsim Sha Tsui. It's pretty convenient and you will find great Indian food there!