According to the PSU calculator at
http://www.extreme.outervision.com/PSUEngine using an i7/920 and a HD5770 (likely overkill), plus making some assumptions about fans and throwing in a tuner yielded a requirement for 471 watts, so the short answer to your second question is "yes." As to the graphics card, yes you'll need one of those too, if only because the kind of CPU-intensive work you're doing would benefit from an Intel CPU, specifically a Core i7. Since Intel + Integrated Graphics = FAIL, you'll need a graphics card. I'm assuming 1080p resolution. If you will do any gaming at all on this system, a HD5770 is probably the lowest GPU you want. If there will be absolutely no gaming, you'd probably find a HD5570 sufficient.
Of course, you haven't stated a budget, but the number of hard drives you're including make me think this is a pretty serious endeavor that will have a reasonable budget.
On the PSU, in general find a model that has full range active PFC (no little voltage switch) and 80+ certification. I'm partial to Antec, but Corsair, Seasonic, PC Power & Cooling, and Enermax are also among the better brands. You're going to need a lot of connectors, so read the PSU specs for those, although you could use some splitters if you have to. Check out the Seasonic X-650. This 80+ gold unit is so efficient and runs so cool that at low loads it does not even need to run its fan, a definite plus for a HTPC.
Oh, on the PSU calculator I think I also figured an additional PCIE x4 card for a RAID / controller for the drives not directly connected to the mobo.