On the going outside thing, could you get those locks that also require a key on the inside to unlock?
As for the stove/oven... how handy is husband? Because he might have to fashion something specific to actually cover the entire stovetop knobs and all at night. Something nice and heavy that requires effort to move and will make noise if she does move it (and that you can maybe hook one of those cheap door alarms to?) to alert you if she's in there. If locking the kitchen door itself isn't an option, depending on how your house is designed (ours is open doorway, for instance, there is no door at all).
