Nuendo doesn't have the sort or field recorder workflow that you see in PT10. However, AVID MC has an automated way of conforming production sound to video by TC. So you should explore that and ask the editors to do it, because its unreasonable for you to sync manualy when they can do it in a pinch, just before they export the AAFs for you. Failing that, all I can think of is PluralEyes.
As for AAFs, install Nuendo 5.1 alongside N5.5. It handles AAFs perfectly, so after you import an AAF in N5.1, you can export the tracks as 'track archive' and import them into your N5.5 session. It's crazy that AAF is still broken in N5.5, one of the most important functions of a post-oriented DAW.
EDIT: sorry, I just noticed you're talking MXF - AFAIK, it should be working in N5.1, but I never get these, so I can't tell you that for sure.