Black Cat is not Gwen Stacy, she is Felicia Hardy.

A next movie without Lizard would be foolish. Connors is already an established character in the series, with close ties to Peter. This would make for a much more compelling storyline than any other villain I think. Of course, they will probably do what they like to do in comic sequels and toss another villain or two in there. Probably Vulture or Mysterio or something.