Well for end to end DVCProHD, all I/O should be firewire. No question about it. But you’ll still want SDI for monitoring and for when you rent an HDCam deck.
The Kona 3 may be overkill, unless you plan on upconverting a lot of SD stuff, or if you want 4:4:4 HDCam SR capability. If neither of those are the case, I would get the LHE or a Blackmagic card and save a lot.
As far as drives. There are a lot of options out there. FC is a ton of money. SANs are great for certain types of projects with lots of editors. Good chance you won’t need it. SATA is faster and a lot cheaper.
There’s a bunch of vendors who sell external SATA solutions. Firmtek, Sonnet, Calldigit, Highpoint, 3ware. Some have RAID 5 (wikipedia if you don’t know what it is) which is great. Some are quieter than others. Some cost a ridicluous amount more than others. But they all essentially do the same thing.
I myself just bought four 400GB drives for $95 each, and put them inside our new Mac Pro. The Mac Pro only has slots for 3 additional drives, but there are extra SATA conenctors on the motherboard. So I put the 4th drive in the optical bay using a bracket kit.