First of all, well just Hi!

Ordered my first Pi and I am eagerly waiting for its arrival and just wanted to check with you guys if my proposed setup will work.
First off, I am sorry if I'm posting in the wrong forum, please move this thread where you (the admins) find it most suitable.
Now to my question and my future setup:
My parents have always wanted a small portable device (pref. loaded with movies) to take with them when they travel abroad. A device to connect to the hotel TV and just chill out after a day taking in a new city etc. Now what I was thinking was to use a Rasberry Pi with the Raspbmc distribution and Plex addon and stream movies from my NAS which will be a Netgear ReadyNAS Ultra 2 w. Intel Atom 1.8GHz and 1GB DDR-RAM.
I was thinking to do this even abroad and the material that will be streamed would be 720p in h.264 but it MIGHT be other material as well (1080p, other formats etc.).
The NAS will run the Plex add-on and I was picturing it to look a lot like this when browsing movies:

The key is to browse movies by cover and automatically fetch meta-data about the movies and pref. subtitle support. Also in big capital shiny letters EASY TO USE. They are not tech-savvy but they are not totally lost either when dealing with tech. Pref. just plug'n'play and at most connect to a Wifi-network from Raspbmc if the hotel does not provide an ethernet jack.
Now to the big question, will it work like that, meaning they can take it anywhere in the world, connect it to the hotels internet and connect to my NAS (via dyndns I guess) and then well, just play movies like they played it at home on our LAN?
Does the NAS have any role in this other then serving movies (i.e. handing out movies, the Pi seems to decode the movies by itself as long as it is h.264?)? If so how strong (processor speed and ram) does it need to be?
Thank you very much for your replies and tips regarding this - TheSwede86