db andtable schemas

Hi there

I am creating a code generator to build our project from our postgress data base

But, what I cant seem to find is the sql to do the following

1. Retrieve a list of tables from a given database
2. How to retrieve a list of table properties from a table
3. how retireve what constraints a table has
4. foreign ekeys
5. primary keys

I would be really greatful if someone could point me in the direction

Many thanks

Jamie