I would like to renew my HKSAR passport. What is the fee and where should I send it to?

Dorothy, you should submit the application by yourself to the embassy or consulate of PRC and your living area should belong to its consular district. Or you can post it directly to HK immigration department.
Delivery by double registered air mail: you need to pay 43USD (32-pages) or 38.5USD (48-page) to the government of HK SAR.
Delivery by express dispatch service: you need to pay 60.5USD (32-pages) or 66USD (48-page) to the government of HK SAR
The embassy also charges 15USD commission fee. Besides, you also have to pay the postage.