Yeah, it was 400pts and they reduced it to 80pts when the file size limits changed.
Yay, there's a sequel to Miasma! The last one was a quality bit of sci-fi turn based strategy, so I'm hoping for more of the same. I'm sure the last one was more than 80msp, I guess they've joined the race to the bottom on pricing. I was more than happy to pay 240 or 400 or whatever it was when the first one came out, but it's a tough sell for a lot of people. The first game is one of the highlights of XBLIG for me.
To the above, yeah, you still need internet access and they haven't announced any plans to change that. What happens when LIVE dies is anyone's guess but I think you've got quite some years before you have to worry about that.