1.) Yes & No,you'll need to get a 5.25" to 3.5" bay converter for 2 HDDs
2.)The card is more than you need. But yes it will do Audio/video over HDMI
3.) Yes the CPU is more than enough
4.) I would go with MythTV
2.)The card is more than you need. But yes it will do Audio/video over HDMI
3.) Yes the CPU is more than enough
4.) I would go with MythTV