multiple wake-up times with pm set

The pmset command will wake and sleep the system on a schedule, but you can only set one such event per day. One option with this is to have it wake at 22:00 and then sleep after 4:00, but it would remain on during this time frame.

The alternative would be to have a script run through your workflow that would execute pmset and update the schedule, but this could get a bit convoluted to set up. pmset requires running as root to modify any settings, so you would have to authenticate, perhaps set it to run as a root-level launch agent, or modify your sudoers file (not recommended) to modify the authentication requirements for the sudo command for a given user.

True and untrue at the same time.

You can set up multiple schedules, but not multiple repeat events. Therefore, if you want the system to wake on July 12th, and then on July 15th, or even on July 12th at 8:00am and then on the same day at 9:00pm, then you can do that with a repeated schedule. However, you cannot do this for an indefinitely repeating event such as having the system always wake or sleep on every Tuesday moving forward.

One way to do this would be to script a schedule for the current week or month, and then apply it, but this setup would require regular maintenance to keep the schedule going.

Does it have to run at exactly 0400 and 2200, or can it run after it wakes from sleep after that time?

If that is the case, you may want to look at creating a launchctl plist to have it run whatever you want at those times. launchd will run them as soon as it wakes up after the scheduled time (or at that time if it is awake).

There are quite a few examples online, but Lingon makes it pretty easy to create the plist and schedule the events. Even with Lingon, you would want to read up on launchd: http://developer.apple.com/library/mac/#documentation/MacOSX/Conceptual/BPSystem Startup/Chapters/CreatingLaunchdJobs.html

An example using Lingon: http://nathangrigg.net/2012/07/schedule-jobs-using-launchd/

Actually that link you posted to has a couple of good comments from readers on how to use this feature, probably as good as you'll get anywhere else.

No. If it misses its schedule because the Mac is asleep, it will run when it wakes.

The Terminal is not something to blindly avoid; it's just a more complex approach to managing your system, which requires syntax (somethign that is not needed for graphical interfaces), so small errors like typos can result in commands not working.

Usually these errors simply give a warning instead of performing the intended task, but in rare cases they can lead to data loss or system destability. The OS X graphical interface has a number of checks to keep you from deleting or modifying important files, but many of these are not implemented in the Terminal.

There are a number of tutorials on the internet that you can search for and try out. Most will get you started on the basics just fine, with the differences only being for more advanced users. Once you know how to navigate your system with the Terminal, then you can advance to viewing and editing files, looking up information like permissions, and then modifying system files to make changes, if needed.