1. Some people recommend a smaller tub, but I usually try and go with a medium size tub around this size. It gives them some room to grow into it a bit and saves you having to purchase more "step up" enclosures. It can probably stay there until is outgrows a medium size hide or around 500-600g.
2. 240 Liters is about a 60-65 gallon tank, which (from what I have seen) comes out to roughly 48" x 15" x 20". This could house an adult snake no problem, but personally I would like something a little wider.
3. There is this previous post.
4. Male or female doesn't really make a difference as to which makes the better pet. Females are generally a bit more expensive and grow a bit larger.