Regarding the gamma issue:
It does not matter what gamma Prophoto RGB uses internally as long as you work in a color managed workflow, preferably with 16 bits/color. The gamma is internal to ProPhoto RGB, so it's nothing you can change.
Regarding the gamma setting of 1.8 on the Mac it's also old stuff, I think new Macs use 2.2. Technically speaking 2.2 is a better value because the steps are more evenly split in the gamma space than with 1.8, sorry I can not explain it better without working trough the math. The reason 1.8 was chosen for the mac was really because it was used in lieu of color management. Printers used to have a gamma of 1.8.
Now, Macs are pretty good at color management so you'd get decent color whatever the gamma, most folks outside the creative arts use the other OS starting with 'W' and neither the OS or their users do much about color management. The other OS and most hardware is probably closer to gamma 2.2.
Conclusion is forget about gamma 1.8.
Regarding color calibration, many experts recommend calibrating for native gamma, forcing the monitor to a gamma not supported by it's internal gamma may cause excessive bending of the gamma curve. This is probably seldom a problem but it's probably good advice.
If you make pictures for the web or uncalibrated environment sRGB is your best choice (well, least evil choice). sRGB has gamma 2.2.
BTW. Windows actually supports color management but few applications use it and I expect that very few PC-owners outside creative arts do color management.
I purchased Michael's Fine Art Printing Video at Calumet (vs. downloading) quite a while ago and I'm finally getting around to watching it - better late than never I guess.
I've enjoyed it quite a bit (have some more to go) and while I realize the video was created a couple of years ago, I think most of the information is still current. There are a few area that left me puzzled though so I thought I'd ask for clarification.
I learned to print years ago with a 'west coast' based photographer, whom I know both Michael and jeff know, so I'm not new to this, but what left me scratching my head was the segment on "output sharpening". Many here may be going "what segment on output sharpening"? That leads me to one of my questions. There doesn't seem to be any information on output sharpening; there's lots of talk about using Photokit sharpener, but nothing substantive for those of us that a) don't own it, can't run it even if we did (it's not 64bit compatible), and c) want to know other ways to handle things in our native applications, such as Photoshop. this seems to be a large hole in the 'craft' of preparing to print, so I'm wondering, am I missing something?
Also, when jeff talks about setting the Prophoto gray gamma to 1.8 (vs. 2.2) Michael questions that and then finally says "OK". I never knew that so my question is should that be done for a PC and a Mac, or is that Mac only? I was also a little unsure about what Jeff meant by copying from B&W to color, so if anyone can clarify this I'd appreciate it.
Thanks for the help. Back to watching...