10 g is good for a hatch. 20 might be good for an adult depends on how big it gets. Don't handle it at all for the first 2-3 weeks to get settled.(but offer food). Important if you use a tank to cover 3 sides with something dark. They're shy and don't like the "fishbowl" affect.
After the first couple of weeks you can handle them as they usually are pretty tame but don't handle as much and as long at first , slowly build to frequently.(except 48hrs after a meal or during a shed because they cant see). They'll get used to you.
I've never noticed a diference in temperment between sexes but females get bigger and thicker.