I think her super tight skinnies show off her figure. But the prude in me feels mildly uncomfortable with that when she's out at a kids party. I always think of those kinds of super tight skinnies as being something you wear when you want to look a little sexy.
Having said all that, she looks great (anyone seen the video of her picking out trees? At one point her back is to the camera and honestly, my only thought was, "my god, that ass!?" with a massive jealous emoticon attached!)
I also don't see any problem with the boots. Others are wearing Wellies? I'd choose hiking boots over wellies any day of the year. More comfortable, look better and just as good for walking around with the kids in this kind of situation.