For diet, the best kind of diet is the kind that adjusts to your needs. For instance, an anti-inflammation diet I'm going on starts you off with a bunch of foods that are known to cause no problems for almost everyone, and then it slowly introduces foods that are otherwise very good, but do cause inflammation for some people (ie, some people react badly to the histamines in bananas, others react badly to the seeds in raspberries), so you can figure out exactly which foods cause you problems. If your diet doesn't make those kinds of adjustments, you'll be gambling as to whether it happens to line up with what your body works well with.
That said, a good generic diet to follow is the glycemic index/glycemic load diet, it's primarily for people with diabetes, but anyone can benefit from it, and unlike any of the fad diets, it's unlikely to hurt you by following it. Also, if you are not already diabetic, it lends itself very well to "cheating" - as long as you eat one food item with a low GI before eating one with a medium or high GI, you'll not end up with a crash. It's also quite possible that following the GI/GL diet could help you with your snacking issue.
Otherwise for snacks, I find the easiest methods is to just substitute the snacks out for something else. Try to make sure that you don't have any problem foods in the house anymore, and when you go shopping make sure you've eaten enough so you're not hungry. You're more likely to buy junk food if you're shopping while hungry than when you're satisfied.
As far as exercise goes, cardio benefits some people and is counterproductive for others. If you've been doing cardio for a while, and you've been making some progress, even if it's small, it wouldn't hurt to keep going for it. On the other hand if you've kept steady at your current weight with cardio, you'd want to switch.
It's really hard to go wrong with a strength program that's based on compund lifts of free weights. A lot of people have reported weight loss success on the Stronglifts 5x5 program. The best thing with focusing on strength is it's a win-win. Either you start losing fat (although possibly not weight due to muscle gain), or if you don't you're that much better prepared to your better base strength to work on a different weight loss exercise program.