If she's trying to find alternatives, it's not going to work. If you're always looking for the replacement, I don't think you can truly commit and eat the way that will help you.
Vegetables. Lots of meat, fat & vegetables. That's all it is (to simplify paleo-life a LOT). Make sure she understands the value of healthy fats. I think you're making this a bit more complicated than it actually is. The best way to avoid snacking is to make sure you eat plenty at each meal. If you/she haven't read a book on this (Mark Sisson's "Primal Blueprint", for example), you/she should definitely do that. If you find the right ratio for you, of carbs to protein to fats, you won't be hungry between meals and over time you will be less tempted to snack from habit.
Asking why an old diet worked is always tricky. It really depends on a lot of thing, but mostly the person. She could be able to stand more carbs than your average paleo-ite, or maybe it was just the lack of calories. If you really want to know, you'd have to analyze exactly what she ate.
And the answer to most of your questions is going to be: try it and see what works. There's nothing written in stone about this, except for no grains, no legumes and no processed crap (and no sugar).