Bulk Load and Extract from PostgreSQL

Hi All.

I want to extract and Load data from PostgreSQL using Libpq C API. Please let me know which approach will be good to
loadlarge number of rows into PostgreSQL(Insert or COPY FROM) and, which approach will be good to extract large number
ofrows from PostgreSQL (COPY TO or SELECT). 
I want to handle all the data types supported in the PostgreSQL.

Thanks,
Sandeep