First, have you confirmed that this card works with LMCE in the wiki? Or at least works with Linux? You should be able to see it on the PCI bus (assuming it is a PCI card) by typing lspci in a terminal. Also, you should see it initialising during start up by typing dmesg in a terminal and looking for the card name.
As long as you see that successfully, it will probably work - when you say it doesn't get detected, do you mean that it doesn't appear during the setup wizard when she talks about TV cards? No idea if they normally do, but my one certainly doesn't and that is known "normal behaviour". Just ignore it and move on.
Can't advise you on Myth setups, but you really ought to choose VDR - it is specifically designed for DVB areas (including Australia). It needs to be tuned before the TV system will work - so do a search on the wiki for the TV tuning instructions, probably search on "dvb-utils", "channels.conf" or "scan -o", find the tuning file for your area and use that to generate the channels.conf file. Then upload that in the VDR section of the web admin and reload the router. Then your TV should work ....
You don't need a TV guide, this is transmitted over the air as part of the TV signal. You haven't really actually described the symptoms of any of your problems, so this advice is general to get TV going.... but I can't tell you anything about your DVD problems, all you said is it doesn't work!