I almost bought FusionGamer for DMCForums, but Omni is good.
The upgrade should happen as follows:
1. Uninstall every plugin.
2. Uninstall the skin.
3. Upgrade the forum.
4. Install the skin. Make modifications as needed.
5. Re-install the plugins that have already gotten 2.0 versions available.
6. Modify the site as you wish.
Also, just to note, if you have s9x media embeds or anything similar, uninstall it. Remove it before you go xf2.0. And make sure that when you upgrade, remove any of the current media embeds. I mean it. Any. It will conflict with the new version. XF2.0 will import new ones.
I had s9x installed in one of my sites, and the media embeds conflicted with the new ones.
You also don't need any widget plugins, it ships with a widget system.
Finally, don't forget the e-mail issue. I had a hard time getting your e-mails. My e-mail address is correct, and I'm not getting mail from devilmaycry.org