Hi Mark
A couple of things regarding your questions...
- Re. protein powders, I would suggest a clean whey protein...not a meal replacement or anything with alot of carbs and fillers. I love Beverly International. I also use IDS but it doesn't taste as good. Pride Nutrition and Dave Palumbo's company (Species) have good protein powders too. If she's trying to lean out, I wouldn't go crazy on the protein powders...but a post workout shake with some simple carbs added (like a banana) is fine.
- No protein bars if she's trying to lean out. Go with real food and avoid the added fillers, sugars, and bad fats.
- Re. grams of carbs/protein per day...I personally do not prefer low carb/no carb diets for active people. Carbs are the best source of energy if she is training hard and doing cardio. What she needs to do to lean out is get herself into a calorie deficit.
For someone her size (5-5, 125 pounds is not very big btw...so she must not have a lot to lose...tightening up should be pretty easy to do), I would recommend something like 1 gram per pound of protein, and up to 2 grams per pound of carbs as a guideline, at least for starters. That would be 125 g protein and up to 250 g carbs. At 4 calories per gram, that gives you about 1500 calories. Then, add a little bit of healthy fats, and you're up to 1600-1700 calories. If she's really active, that should lean her out. If it's too many calories for her activity level, then cut the carbs down to 150-200 grams. I don't see a need to go down to 100 or lower on the carbs, personally. If she's not contest prepping, she doesn't need to suffer tremendously LOL...and you want to set up something that she can stick with long-term.
-For leaning out, I'd recommend 4-5 cardio sessions per week, preferably in the morning on an empty stomach, but anytime is OK as long as it's getting done. 30-45 mins, relatively high intensity, or intervals is even better.
Also, weight training is extremely important. She should be training at least 3-4 times a week. 5-5 and 125 pounds isn't a TON of muscle, so it wouldn't hurt at all to push the weights a little (i.e., go heavier) even while she's trying to lean out.
There's a million answers to your questions, of course... this is JMO... I'd love to hear what others think. Juiliette gave some good advice too.

Let us know if you have any other questions.