Macau casinos
Hong KOng does not have casinos. You can take the ferry to Macau, about an hour away, but you have to reserve your return trip. Book the latest ferry back, you can always leave on an earlier one, but not vice versa. Bring your passport with you, as Macau si independent from HK. Both are part of China, but require visas from certain nationals.
BJ is not very popular there. They play strange asians games that I did not attempt to learn. The casinos are not very large but very crowded. The largest is Lisbon in downtown. Don't even go there. My favorite is the boat casino within walking distance form the ferry. They have only one BJ table. Min $100 HK dollars last time I went (about $13), most others are min $200 HK. Rules are not very good, double only on 11, perhaps 10, not sure. I read in Ian Andersen's book they allow double on 9 in some, but soft 19 is considered a 9 not 19 if you double on it, and get a 2, it's considered 11 not 21!!!
I have been to Australia, and I think the casinos allow you to play if you're 18. Considerign that the conditions in Australia are much better than Macau, I would advise not to waste your money to get an inferior game in Macau.