1) Pretty sure I'll need a RAID array - but what configuration? I was leaning toward RAID 5, but then saw that Harm called it a non-video array (?)
Raid 5 is better in high I/O situations, whereas Raid 3 is better in high transfer rates. As long as the raid is not degraded, the differences are small and a raid 5 controller is usually less expensive than an Areca controller, which is needed for raid 3. But when one looses a single disk, the rebuilding of the array takes much longer on a raid 5 than on a raid 3, unless the parity disk on a raid3 is the one to go. If a data disk dies, a raid 5 requires reading and writing to all the disks in the array, a raid 3 needs to read from all disks but only write to a single disk. The rebuild overhead is much larger with raid 5.
2) and will it work with most new mother boards? or does it require a hardware card?
Yes, but with a severe performance penalty, so effectively you need a hardware card for parity raids.
3) also, interior or exterior RAID drives? is heat a problem?
Interior is much easier and heat is no problem. I have 17 disks internally and never had any problem with heat, despite overclocking.
4) Plus I keep reading about Throughput - but not sure how to calculate my needs. I found some crazy formulas online - but is there another way?
If all you do is single track editing, throughput is irrelevant. If you often have large numbers of tracks using hi-res material, throughput requirements will sky-rocket. There is no simple answer, but generally, the higher the better. Throughput is often the bottleneck in modern systems.
Look here: http://forums.adobe.com/thread/662972
Thanks for the info.
I'm doing a lot of layering and effects, so you think I'd be okay with a hardware-card controlled, internal RAID 5 (4 disks)?
and then a seperate HDD for a scratch disk? I guess I'm not sure what I'd need to play back 100MBPS HD video? would that play from any HDD?
Pretty sure I'll need a RAID array
You may not. 100Mbps is also the data rate of DVCPRO HD. I've not had any issues with this working off a single modern drive.
If you need 10 layers at the same time, it might be an issue. But for many editing purposes, a single drive might work just fine.