Highest power use in Summer for the aircon (can be avoided, if you can open the windows and use a fan) and in Winter for the heater, if you enjoy temperatures higher than 5-10 degrees inside.
3. Two possibilities: fixed line or bottle. A small bottle that is knee-high costs around HK$ 180 and lasts about 6 months for cooking only, high rise buildings have a fixed line for gas.
4. Depends where you live. In the new territories, where PCCW has the monopoly, it costs about HK$400 (but that could be for three months).
6. Eating out for HK$80 per day might be possible. A Double Cheeseburger at McDonalds is about HK$8. A bowl of steamed rice is about HK$10 at a chinese restaurant. We pay HK$5,000 for two per month for groceries and utilities, but eat out only once a week.
7. Income tax is paid yearly. You pay 75% of the tax to be expected next year (provisional tax) plus the difference between the provisional tax last year and the tax to be paid for the actual income. Tax year ends 31. March. So your first ever tax payment might cover three years. If you don't have that money then, you can get a tax loan from your bank.
9. Everything is negotiable, except the fees for the government, tax, utilities, transport and similar things.
You need to add to the rent: 2 months deposit, one half month rent as agent fee and stamp duty.