Didnt they have Gwen's name on a tombstone in the first one? I have no idea what they'll do with her (though I hope she takes MJ's spot in Peter's life, as I hate MJ) since they drew heavily from her death scene in the comics for the bridge scene in the first film.
Anyway, I really like Topher Grace, and I'm sure he'll do a great job, but he wouldnt be my choice for Venom. I see Eddie Brock as a more creepy guy... I think my problem with Topher is that he sort of looks too much like Tobey, and I can easily picture Topher as Peter Parker.
Ah well, I'm sure it will be great anyway.
But on another note... Sandman? Of all the neato villians, why Sandman? Ugh.