If you are running a PC then probably just use premiere and after effects as you won't outgrow them in a hurry, and there are plenty of plugins available for doing filmgrain, B&W effects etc.
Some advice that you can take or ignore
1) Rip it to B&W as a first step, it will save you a truckload of disc space - you can keep the original on disc if you want to tint it later etc.
2) Try and storyboard/script out your idea to get a rough feel for how it will work (you can do this while waiting for your gear)
3) Next do a really rough cut edit - don't add any effects in or play with stuff to much, just get your edit of the story down, and lay your subtitles in to see if the story works - stay in this stage till you get something that hums.
4) Only then start to dub in the audio, play with effects/transitions/fun stuff.
As for the process, you will need lots of hard disc space, make sure you format using NTFS and then an easy set of steps would probably be.
1) Download DVDShrink - it is free
2) Use it to reauthor the DVD disc to just rip the movie itself, leaving all the extras and stuff behind. It is a three click process - very easy, and rip it down to a single vob file by unticking the 'split' option.
3) Download virtualdubmod or virtualdub and avisynth - it is also free.
4) Load the VOB file into virtualdub, make it B&W using the inbuilt filters and save it back out in a format that Premiere (or your editor of choice) can read. You may want to add timecode at this point to make your life easier later on and save out a timecoded version to use as reference.
5) Start doing your edit
It is a fun idea, do you intend just having the German and French voices there for atmosphere but have the subtitles tell a totally different story?