pg_dump/psql: Select a server and automate password

Greetings!

On my computer, I have a copy of a customer's database for which a full backup file would be about 300 megabytes long.  There are several history tables that are not needed for day-to-day operation of our system.  I came up with a DOS batch file that consists of a sequence of pg_dump commands.  The first dumps the database's schema, and all the rest dump the required tables into individual files.  A companion batch file issues psql repeatedly to recreate the database and the tables. 

On my computer, the batch files work fine.  I run them and they happily call pg_dump or psql as many times as they need to, and I don't need to do anything. 

I just uploaded the batch files to our customer's machine, and a couple of questions occured to me.  First, pg_dump asks me for a password every time it is invoked.  That doesn't happen on my computer.  What is likely to be set up differently on my computer so that I don't need a password?

Second, I see no way to select a server in pg_dump or psql.  I am connected to a computer that was set up for my use specifically for testing.  In PGAdmin on that machine, I have a server talking to localhost and a server talking to the machine that hosts the production database.  I would like to run my batch file on the testing machine, but how do I tell pg_dump to use the server that talks to the production machine?

Thank you very much!

RobR