I went there about 10 years ago, that was when you were not required to get a visa. The entry was given at the airport.
I may suggest you however Hong Kong is one expensive place to visit. It's not that fun either except for all the futuristic buildings and the scenery. View from the Victoria Hill is quite amazing.
Other than that, you will have hard time finding Halal food if you are Muslim. You can rely on the Fish-o-Fillet at Mc'Donalds like we did for the whole week. Hotels are really expensive as well. All this was 10 years ago, therefore I think you can expect 10x more inflation now.
However you may disregard all this if you have direct information from someone else in Hong Kong you know of. As of the Visa, there is no need to contact agent, just go the embassy and submit the application yourself. Agents just rip you off for nothing.