The fact the original came to PS3 means the sequel will, if it was going to be Microsoft exclusive then the port would have never happend?
As for simultaneous release? I'd imagine so, I don't see the value in Microsoft buying timed exclusivity on a sequel when Ps3 owners expect it to come to their console.
Also I think it's sales should be fine on Ps3 if it's a simultaneous release. Ubisoft's port of Tom Clancey's generic game #4 (Totally forgot the name) had iffy sales on PS3 but the sequel which release simultaneous is a million seller now.