You do realize that all the iPhone 3Gs are made in China. They all look the same on the front and the back. What do you really want to know, just explain what you want to know in a single post. You can ask more then one question at a time.
The iPhone 3G serial number and IMEI are printed on the SIM tray. If it has two (2) SIM card slots then it is a fake. Oh and if it can't sync with iTunes then it's a fake.
These are the valid part numbers for iPhone 3g sold in the Hong Kong Market: MB489ZP/A, MB496ZP/A, MB500ZP/A. If one of these are not on the packaging, then it is not really a Hong Kong iPhone 3G phone.
Dave