I just got a new TSU 9600. I can't figure out if there is any way to make the network option work as it is or do I need to get an extender.
Any suggestion about the extender the wireless or the wired one?
Is there any benefit on using two TSU 9600 in the same house; as an example one downstairs and the other in a media room located upstairs.
Thanks for yr suggestions.

In order for wireless to work, you will need an extender. The remote will be able to connect to your existing 802.11G network, but without something to blast the IR codes that will be going through wireless, it seems unnecessary. This is where the RFX9400/9600 comes in.
If you aren't going to be using or planning for RS-232 in the future, I would go with the RFX9400. It can be connected through a wired connection or extend a wireless connection, so in those terms its pretty flexible. You could also use it in stand-alone mode so you can hide all your equipment and the extender in a closet and hide all the devices and wires.
As to having multiple remotes, there is really no benefit other than the fact you do have two remotes, but you can make a configuration to cover as many parts of the house you need to.

Note that you can setup your 9600 on a network to control a variety of devices via TCP/IP. Out of the box, the Escient Music Server can be controlled WITHOUT an RFX9400/RFX9600. If you need to control devices remotely using IR, you will need an RFX9400/RFX9600. If you need to do Power Sense, Relay Control, or RS-232, you will need an RFX9600.