A PBEM game is indeed very unlikely to crash: even a major game bug can be recovered by rolling back one turn (or a few turns if it is really major), and I haven't heard of any such bug. I also have the fatherland files and the turn files backed on one mail, so a computer crash would not be enough to crash one of my PBEM games (and even if I were to disappear, Gandalf Parker could give you access to my mail, allowing the game to still go on).
Turn files can be sent to both players; that was my plan (and what I do in the Entwined Destiny game, where six teams of two players fight it out), and it is actually less work for me.
(Though separate mails only take a few more seconds per turn) You could also not set up any password, making it easier to browse the files of your team.
The map is available on Arryn's site I think:
www.dominions-2.org
I should learn to type faster. Either that, or I should be less verbose.