Welcome to the forum and the world of chameleons!
Veiled sexing...
http://www.veiled-chameleon.com/care-sheet.html
It's not advised to put two veiled chameleons in the same cage past the age of 3 or 4 months because they will breed too early and stress each other out as well.IMHO in captivity it's best to wait until the female is full grown before mating her...at about a year is a good age IMHO.
Regarding feeding and gutloading...I use a wide assortment of greens and veggies such as dandelion greens, kale, collards, endive, escarole, squash, zucchini, sweet potato, sweet red pepper, carrots, etc and a bit of fruit such as berries, melon, pear, apple.
It's important to provide appropriate temperatures for the female because it aids in digestion and nutrient absorption. For a female veiled...I keep the temperature in the low to mid 80's F.
You need a source of UVB light (direct sun or UVB long linear tube are the best sources) so the chameleon can produce D3 so that it can use the calcium in its system.
Water should be provided through the use of a dripper and a mister.
Since most feeder insects have a poor ratio of calcium to phosphorous it's important to dust the insects just before feeding them to the chameleon with a phosphorous-free calcium powder at almost every feeding to make up for it.
It's also recommended that you dust twice a month with a phosphorous-free calcium/D3 powder to ensure that the chameleon gets some D3 without overdosing it. D3 from supplements can build up in the system but D3 produced from exposure to the UVB will not as long as the chameleon can move in and out of the UVB at will.
It's also recommended that you dust twice a month with a vitamin powder that contains a beta carotene prOformed source of vitamin A. PrOformed sources will not build up !like prEformed sources will so this leaves it up to you to decide if/when your chameleon needs prEformed vitamin A.
It's important to have an egglaying bin in her cage once she's sexually mature (gets the yellow to mustardy spots) so that she has a place to dig to show you that she's ready to lay eggs. (Once she is receptive she will also get bright blue dots.)having the bin in the cage means you won't have to worry as much about missing the signs that she's getting ready to lay....roaming the cage looking for a laying site, drinking more, maybe eating less, etc.
Hope this helps!