Can Prores files be exported from Premiere Pro CS5 on a MAC? The Prores codec is installed on the MAC.

Yes, we do it routinely.

Yes. As I type this I have ProRes 422 files queued in Media Encoder.

ProRes encode is not installed unless you have FCP installed.

You can play back ProRes on Mac/Windows, but not "write".

Or...you can get a KiPro and an SDI card and record the ProRes file off-board.

I just downloaded the ProRes codecs and installed them and no issues using Premiere, After Effects, or just ripping files around with Media Encoder.

I export to and from prores all the time as it is my preferred editing codec when I have time to transcode.

Does this mean I can place, say, native 5DII and XDCAM files in a Prores timeline, rendering everything in Prores along the way (ie: prior to export)?

Sorry if this question sounds naive, all my timelines in FCP have been Prores by default for so long now I've become reliant on it, but I'm another person looking to jump ship.

Being able to render footage from all different sources in a 10 bit 422 colourspace was one of the features that made FCP attractive to me. If I can't do this with Prores in Premiere, what is the alternative, buy Cineform?

Cineform is an alternative to ProRes, yes. However, since PrPro can edit completely natively with just about every format out there, there really is no need to go to an intermediary. Just because you've got a 10 bit 4:2:2 file doesn't necessarily mean that all that info is there. In fact, trying to take, say, an 8 bit 4:2:0 file to 10 bit 4:2:2 can lead to some nasty results as the encoders try to come up with the missing information. Staying native until your final export will ALWAYS give you the best results. The ONLY way you'd benefit from a 10 bit 4:2:2 or 4:4:4 file is if you initially shot your footage that way (or you were bringing it in from film stock). And even then, the original file you shot (or captured) would be better than transcoding to ProRes or Cineform.

There are speed boosts available for rendering by using Cineform if you've got the associated third party hardware to go along with it, but if you've got a strong machine and Hardware enabled MPE and CUDA, then PrPro really does just about as well as any of them anyway and you'll probably lose any time gained in your transcode.

Yes, edit natively as long as you can. However choosing a good render codec for a sequence is also important, both for performance (encoding/decoding is not accelerated by CUDA), and quality (adding another layer of compression might not be the best way to preview your footage).

Therefore personally I always try to go for 8-bit or 10-bit (if there's a lot of color correction involved) uncompressed. Final master is either ProRes (Mac) or Cineform (PC).