Ok with the flirt. Watch her. Does she do that with the other women? Some people are just touchers, when they talk to you they touch your arm, hug, rub your back a little. I've had both men and women that are like that do it to me, but they also do it to everyone else.
If not then, the best thing you can do is talk about your wife. If you keep bringing her up the lady will get the hint. Like this,
"Oh your arms or so nice and firm."
"Thanks, my wife and I like to keep fit."
"You look great today!"
"Thanks, my wife really loves this shirt too."
Just keep bringing it around that way, she'll get annoyed and leave you alone. I've seen some of the dad's do this. I've done it to a couple of gents. It works.
The gossip, you can't stop her from talking about the other woman to the other women. You can walk away from her when ever she says it to you. You've already stated you don't appreciate it, didn't help. The best thing to do is roll your eyes at her and ignore her, or change the subject.
Better yet, since this is the new hot topic, tell her you don't condone bullying. That will probably shut her up.
Kudos to the other woman for not letting this woman run her off. If you like the lady that is being bullied, I would make an extra special effort to talk to her. If the playground bully sees you two be chummy, she might leave you out of the hen pecking.
I actually feel kinda sorry for you. It's tough for a guy to step into a woman's world and handle it gracefully. Keep trying. :)