Is HDV really an MPG format and should Premier be turning it into an MPG before editing?
Yes HDV is mpeg straight from tape.
If so, does this mean when I output the project, the file will get re-compressed again, and how bad does that re-compression screw up the HD video?
Yes is gets recompressed same as DV.
What do you actually DO with this HDV once you have it edited? I imagine I can output it back to MiniDV and tell the HV30 to record it in HD, although I haven't tried that yet. And then you can plug the camcorder into the Hi-Def TV set via HDMI and watch it that way.
Yes write it back to tape and play it on a hd-tv or make it into BluRay (BR).
I know Blu-Ray recorders are available for installation into my system, but haven't decided to do that just yet, although its my understanding that Premier Pro 2.0 will in fact output to Blu-Ray (??? yes/no??) If so, then that's probably the best way to go I would think...
I do not think Pro 2.0 does BR, no quite sure. Can't remember.
But I have also been told that you can actually write some HD onto a regular DVD-R if you keep the project down to about 10 minutes. If so, how do you tell Premier to do that, and then how would you play it back? Would a regular old DVD player recognize and play back the 10 minute clip in HD? My gut tells me "no" but others are telling me "yes."
Yes you can put hdv on a BR but you need a program like Encore CS3 or higher to make a BR-image. This image is burned on a regular DVD with e.g. Nero. About 20 minutes will fit on a dvd. Then you will need a BR-player to play this dvd.