nature of visa required

Hi, HK and mainland PRC have different visa regulation, you can apply for a visit visa to HK through Chinese embassy in Pakistan. The application may need to be sent to HK Immigration Department for approval if necessary. But generally, the embassy itself can issue it within their right. For conference, invitation letter is required.
I don't think that what you said about no.2 is true, so don't worry, just submit your application to the embassy during their working hours.