The NO products he recommended are vasodilators that give a you a better "pump" during workouts. They allow more blood into your muscles.. DON'T take them during cardio, unless you want to feel super light headed and/or pass out. Trust me.

Also, you don't have to go with what he recommends.. Walmart actually sells a nice Body Fortress NO product that's cheap (thats the only sup I get from wally world other than vitamins).
5'2" and 100lbs. That's medically underweight. You shouldn't be trying to get "cut" or lean.. how could you be any more lean? You need a muscle base to appear toned. At only 100lbs I don't think you will have much.
What you need to do is eat a good clean healthy diet of fruits/veggies/lean meats and the occasional red meats. No fast food..sodas..etc. Take in MORE calories than your RMR (Resting Metabolic rate) which for you is about 1400 calories. Plus the calories burned while working out.. say 500-800 a day to be safe. So.. to bulk up and not gain fat (again, think CLEAN diet) you need to eat about 500 more calories a day than your body consumes. 2400-2600 for you.
Now, you will need to adjust this to fit your metabolism, daily activity etc. If you currently eat 3000 calories a day and don't gain weight then your obviously have a high metabolism. (Which I bet you do) Increase calorie intake accordingly. Also, try to eat 1 to 1.5 times your body weight in grams of protein daily. A good way to do this is with whey protein. Idk where you live but SAMS club here has a good deal on Whey, 23G per serving and only 130 calories. Be careful of some wheys that are a lot of protein but also TONS of calories per serving. On a good clean bulk/workout plan you should gain about 2lbs of mass per week.
The goal here is to build muscle mass and bulk up cleanly to avoid fat gains. Then..once you have a nice base of muscle, you "cut" or lean down to appear toned.
I'd definitely throw in leg workouts in your weekly routine. Keep it interesting and don't over work any one muscle too much each week.
Take it easy at first.. don't overload yourself with workouts. Here's an example.
Monday - Chest / Tri's / Abs
Tuesday - Legs
Wednesday - Abs / Rest
Thursday - Back / Shoulders
Friday - Biceps / Abs
Weekend - Rest
Right now I'm in the "cutting" stage.. eating less calories than I burn and doing a little cardio / interval training in with my heavy lifting.
Hope this helps.
*typed up real quick..probably full of grammatical errors.
EDIT: Were only 2 posts when I started typing that XD Key-J posted a nice link.