You said..."About how many crickets do young veilds eat a day?"..I feed hatchlings as much as they can eat in a couple of minutes per feeding. For adult females veileds you don't want to overfeed them because it can cause them problems with egg laying and clutch size, etc.
You said..."what percentage of their diet is greens?"...some will eat a lot of greens and others won't even touch them.
You daid..."is it okay to use a 10.0 UV light?"...I have used the Repti-sun 5.0 for years...but there are others that are just as good. Some compacts and tube lights have been causing photo kerato conjuctivitus though...
http://www.uvguide.co.uk/index.htm
Two other good sites...
http://www.chameleonnews.com/
http://www.adcham.com/
Appropriate temperatures for basking will aid in proper digestion thus help with nutrient absorption. A regular household incandescent bulb in a hood of a wattage that provides the proper temperature makes a good basking light.
Exposure to UVB (that does not pass through glass or plastic) allow the chameleon to produce vitamin D3 which allows the chameleon to use the calcium in its diet.
A balance of nutrients is important for good health. When looking at a balance its important to look at what you are feeding the insects and the chameleons and what you are using to supplement/dust the insects with.
Calcium, D3. vitamin A and calcium are the four main players in bone health and need to be in balance. They also play other parts in the body.
Most insects have a poor ratio of calcium to phosphorous so its important to dust the insects before feeding them to the chameleon with a phos.-free calcium powder at most feedings.
Gutloading the insects and feeding them a nutritious diet is important too.
To ensure that the chameleon gets enough vitamins, I dust with a vitamin powder that has a beta carotene source of vitamin A twice a momnth. Beta carotene won't build up in the system like preformed vitamin A will. Excess preformed vitamin A can prevent the D3 from doing its job and lead to MBD.
If the chameleon only gets UVB from a tube light and no direct sunlight, then it might need the insects to be dusted twice a month with a phos.-free calcium/D3 powder.