It's getting late in my end so pardon my brevity.
The Alexa can shoot in the ARRI RAW format.
10 stops for film seems low to me. Kodak 5219 35mm film has been measured at 14.5 stops. Alexa and the Sony F3 w/the S-Log upgrade both have measured better dynamic range than the RED MX. I'd take a serious look at the C300 as it's low light is supposed to be excellent and it has a significantly lower operating and workflow cost. But, honestly, camera technology being what it is today there really isn't a bad choice once you get into the 5 figure range. Some cameras are better at X some are better at Y and it comes down to does your shooting require more X or more Y and that's the camera you should go with.
Unless what you are shooting can be sold later as stock footage there's really no point to try and 'future proof' your film like that, IMO. Maybe shoot 4k, so you have it someday if you actually need it, but go down to 2k or 1080p for editing and finishing. Being 'only' 1080p didn't seem to hinder "Avatar" much.
As of now Premiere on a Mac Pro w/a CUDA-compatible GPU and a fat eSATA or Thundberbolt RAID is going to integrate the best w/R3D files. If you can get a RED Rocket card ($5k-ish I think) all the better.
Finally, post production is part of pre-produciton. Do tests now and figure out what things work and what things don't. Waiting until you shot most/all of your footage before
It's like planning to drive from NY to LA. Do you just leave NY and hope that you eventually end up in LA? Of course not. Before you even get into the car you pull out a map, look at where NY is, look at where LA is then look at all the millions of roadways in between and plot your specific course (yes, I realize that Google maps and GPS make this analogy a bit antiqued but just humor me).
Final finally, you are a tech buff, he's a movie buff... is anyone involved a filmmaker? A DP? An Editor? A DIT? I ask because shooting RED and sticking w/the R3D's is, and I'm not exaggerating here, the most PITA and the most error-prone of any modern workflow and it would really make you guys less likely to go postal if there were people involved that had an intimate knowledge of post and production. All the flexibility that sticking w/R3D can give you is also a whole lot of rope to hang yourself with. I'm not saying it can't be done, but when a number of pros that do this type of thing day in and day out still get frustrated by it...
Final final finally, don't forget to triple your storage needs. 1 copy of footage to cut with, 1 copy of footage says at the director's house, 1 copy of the footage stays at the editor's house. Or something like that. Basically, if someone's house burns to the ground you don't want your only copy of the footage to go with it. And in the unfortunate event that does happen you don't want to be left with just a single copy of all your footage (which of course would have to get backed-up immediately).
Final final final finally, shooting a movie so it looks dark does not entail actually shooting the movie in the dark. It's all about relative lighting differences. Cameras need to be able to 'see' what's in the shadows otherwise it turns to noise and instead of a nice smooth, black shadow you get a shadow that's full of ugly, crunchy artifacts.
I mention this because I see it all the time (even from people that have so much experience I'd think they'd know better). Your image out of the camera should look flat (the highlights shouldn't be over exposed and the shadows shouldn't be under exposed) and when you do your grade is when you'll play with your levels to get the image to look beautiful.
If you watch the behind-the-scenes of movies that shoot a lot at night you'll get an idea of just how much light is actually used during production.
Yeesh, if this is me being brief I hope I never start to ramble...
Lethal
P.S. If I sound negative it's not because I'm trying to dissuade anyone. I'm just trying to keep people from making the same mistakes, or similar mistakes, that I've made.