Disk Size can reach 36"+, females tend to get larger as well as grow faster than males.
As far as food goes rays really need a variety, for smaller/younger rays black worms and ghost shrimp(although they contain very little nutritional value!) are good for when you first get them but you want to wean them onto market shrimp/a quality pellet food(I recommend hikari massivore) as soon as possible. To add variety to a rays diet you can add live crayfish as long as you take the claws off of them, nightcrawlers and even feeder fish as long as you don't buy them right from the lfs and then throw them in the tank you want to make sure you quarantine them first or have breed them yourself so that they're disease free.
As far as I know they don't prefer any specific type of lighting; maybe somebody else can give you better advice in that area.
In my personal experience they prefer the temperature slightly higher than most other fish-around 83F. Stingrays can not sense the heat from a tank heater and can burn themselves on the heater! Make sure to buy/make some sort of heater guard, and if you have a sump it would be best to put heaters in that.
Avoid sharp gravel or any sharp decorations that the stingray could cut it's disk on. I would avoid gravel altogether and just stick with either sand or barebottom don't overdecorate your tank either stingrays need a lot of bottom area to swim.
