Part of it has been resolved. This could be helpful for others.
You can get zip/postal code information by the function available in the location module i.e.
location_get_postalcode_data which accept Location parameter as array
@param $location
* Array. the location data
* -> the values are:
* street => the string representing the street location (REQUIRED)
* additional => the string representing the additional street location portion in the location form
* city => the city name (REQUIRED)
* province => the province code defined in the country-specific include file
* country => the lower-case of the two-letter ISO code (REQUIRED)
* postal_code => the postal-code (REQUIRED)
Also I did some modification in my country specific .inc file available in supported directory to fetch extra information along with default lat-lon info.
但是,如果在数据库中无法提供齐普/邮政编码,则有第二部分有待处理。