1) Poison Ivy: As far as I could tell, the tree was supposed to be symbolic of Poison Ivy's bad karma catching up with her. The only thing sexual about the story I noticed was the art.
2) Catwoman: FYI, female superheroes are allowed to be injured without being fridged, same as male characters. Whether or not an injury is WiR-worthy usually depends on the response of the attacked. What did Catwoman do when she recovered? She took away from him the one thing he really cared about. If that's the actions of a weak character, then Batman, who has never really had the upper hand on Hush, must be really pathetic. On the other hand, Selina's own series had her getting pregnant from a guy she barely knew and then give up Helena when the writer got tired of writing about her.
3) Zatanna: I don't see why you think that a woman can't be someone's potential love interest and a strong character in her own right. And I also don't see why Dini should base his Zatanna off a version that wasn't even in continuity. This is really a topic we're never going to agree on, since I personally believe that Grant Morrison is a very sexist writer. His Zee series wasn't too bad, but his bitchy Lois Lane from All Star Superman and his fridged Wonder Woman from Final Crisis really got on my nerves. And his Bulleteer series seemed to imply that all women were obsessed with men.
4) Ventriloquist: Seriously calling the new Ventriloquist "vapid?" I don't think so. Her character was not as complicated as Wesker's, which is expected considering he had been around a lot longer than her, but she had an interesting backstory and she was very intelligent. To me your explanation for why you don't like her seems actually pretty sexist. Your basic explanation is oooh, she's a woman. Women can't be scary or creeped or messed up.
Her being Hush's girlfriend did annoy me, but not because it seemed sexist. Dini's tying Peyton in with Matthew and Hush just seemed like really lazy writing. Like he couldn't think up a new female and decided to stick her in last minute. Also, it messed up her character as had been established before.
Frankly, even if I believed the examples you list to be truly sexist, Dini would still not qualify as one of the more sexist writers in comics.