My basic understanding is testnet is a test blockchain similar to the main BTC blockchain, gigabytecoin and others are using it to test their software at a much less difficulty allowing you to make checks easier.  From what i gather pushpool isnt quite designed to run on it as the difficulty is so low compared to the main BTC blockchain. 

The default server.json has the statement:

"stmt.pwdb"':""SELECT password FROM pool_worker WHERE username =?",


So you need a database defined "pushpool" with a table called "pool_worker" with at least "username" and "password" fields with values that your miner will use.  These fields are checked from the above statment, which are your miners username and pw.

Can you telnet to the 8344 port from your other box?