What are the ideal settings for my TC with Shaw's Cisco DPC3825 router/modem

Unless you specifically need to have the TC perform as the main router for your network, life will be a lot easier if you configure the TC to operate in Bridge Mode.

Whether the Cisco modem/router or gateway can possibly be configured to act as a simple bridge mode modem is one thing to consider.

Whether Shaw would support you in the event of any connection difficulties with the modem/router configured this way is another.

Since Shaw is your provider, it might make sense to talk with them about best practice as far as configuring the DPC3825.

Once you have that information in hand, you will then have the answer on how best to configure the TC.....which will very likely be in Bridge Mode.

Typically best setup is to put Cisco router in bridge mode or alternatively put TC in the DMZ.

Then turn of Cisco router wifi if it has it.

This way you'll get the apple routers full features like Wake up on LAN, GUEST NETWORK, remote access to disk from Internet, back to my Mac, etc

Here is how to get bridge mode:

http://forums.redflagdeals.com/cisco-dpc3825-upgrade-basic-setup-bridge-mode-cab le-modem-mode-1142802/