cresteds are very hardy and great first lizards because of the ease of the care they require. they do not require any supplemental lighting, ambient light from a window is plenty to give them a day/night cycle. since cresteds are nocturnal they would be fine for your friend's schedule--he could feed and care for them after he gets home at night when they will be awake.

3 adults should fit comfortably in a 29 gallon tank, but the tank should be oriented vertically rather than horizontally since cresteds are arboreal. also keep in mind that males should not be housed together and a male and female kept together will most definitely result in eggs so if he wants more than one gecko he should probably look for females.