BluRay is not region coded, so I believe you can buy the japanese system and all games should work fine. As for metal gear itself, I think it has dual audio.
I don't get the big deal out of the 80 gig anyway. I was going to replace the hard drive down the road due to the fact that I plan to own many games that will most likely require massive installs. I just thought that with that mentality, it was a deal since you get an extra controller. Also...
I noticed this deal at a Gamestop in Bakersfield, CA, 40 gig PS3, with Metal Gear 4 and an extra dualshock 3 controller for $484.99. I didn't see any advertising for it other than a small poster at the entry, I confirmed it with the store manager though, and at 2 other locations. Not sure how...