The general ruling is 2 months deposit held by the landlord for the duration of the rental of the property, this is held by the landlord and not the agency as is the case in many other countries. The monies will be returned at the end of the lease without interest and less any damage to the property outside of 'fair, wear and tear'
Some corporate (and occasionally private) landlords require 3 months rental deposit.
1 months rental is also payable in advance of the start of the tenancy, this allows you time to set up an autopay to the landlord for the following months and term of the tenancy.
Stamp duty is a 1 off payment to the government of HKSAR and it registers your tenancy with the Government.
Agents fees, again as a general ruling agents fees are 50% of 1 month rent.
Utility deposits will also be required, but these are depoendant on the size of the property and the gas/elec appliances in the property. Water is quite cheap here in Hong Kong so you may have a pleasant surprise with water bills.