Hong Kong entry permit for PRC passport holder working, studying in Singapore

Dear Sir/Madam,
I am a PRC passport holder, I have been working in Singapore for 4 years. I would like to visit HK for travel for max. 7 days on 10 Aug 13. I would like to enquiry about the entry permit application.
1. How long does it take for this entry permit applcation for me?
2. Where can I apply?
3. Is it allowed to ask someone to be my representative to apply because I think I may not be able to go due to my working hours?
4. My friend is a PRC too, he is studying in Singapore, but his student pass is going to expire in Oct 13, because he is having summer holiday now and his next semester will start in Sep 13. Can he apply entry permit to HK too ? Is there any other special documents that he needs to prepare? How long does it take?
Thank you very much.
Jenny