- Do ghosts eat and drink?I don't think ghosts do eat or drinks like we human beings do. Ghosts are transparent and they hasn't alive bodies like us. So eating normally wouldn't make sense and they would probably not taste the food either. I have no idea if there are "ghost food". But they can't digestive normal food.
- Do ghosts need to sleep?Ghosts are restless creatures and since they doesn't have a body like us human, where it have to repair new cells (in the same way as us), they probably doesn't need sleep either. They doesn't get tired.
- Why do ghosts haunt people?It really depends from ghost to ghost. Some wants to do unfinished business done, some wants to say hi and other wants to take revenge at people they dislikes.
- Are ghost evil or like 'normal' human beings: can be kind etc?It depends which spirits type they are. Some resemble more at demons, some are more like human beings. Some ghost can be kind. It really depends how the person was when they lived and which personality they have.
- Why do ghosts wear clothes sometimes, other times sheet/shrouds?A tradition from the past were covering corpses in shrouds/sheets. Perhaps therefor they sometimes appear in the white stereo typically shrouds sometimes, later became a Halloween cliche. Ghost wants to be comfortable and present them in a way they likes, therefor they wear clothes. They are so used to wear clothes because they wore them when they were alive.
- How do you think the ghosts looks alike?It depends at how they want to present themselves. Sometimes they prefer to be invisible, other times they presents as a shadow to just show they are there without people can easily identify them. If they wants to be recognized, they appear as how they looked alike when they were alive, just in a transparent version. If the ghost was a transgender, they would present themselves in that gender they identify themselves as, not the sex they were assigned at birth (I assume).
Ghosts has lesser colors than alive humans and animals. They hasn't strong colors, but weaker and more gray/transparent color, I guess so. How much colors they have might depending at how they want to present themselves, how the light in the room is and how the energy is. Ghosts are paler than what alive human beings are. I assume peoples with the Northern-European looks would look very pale or vampire white as a ghost, but a person who's tan or has a darker skin tone would look more gray. The most dark skinned one would look middle-toned gray. I just assume, I have no idea.
- If ghosts wear clothes, can they change their clothes, appearance etc?I would believe it would make more sense they could change appearance, clothes etc. If they can turn themselves invisible etc, off course they would have ability to switch which clothes they wears too. That seems more logic to me. Anyway, wearing the same thing are boring as well.
- Why do ghosts often being pictured with flowing clothes, hair etc, and why do some of them also being imagined with chains?In movies, TV-series, comics etc. they might appear with a extra ghostly appearance to impress the audience and being more entertaining. It would also be more scary and exciting. Some ghosts might wear chains because they wants to demonstrate they didn't have a easy life. Maybe they were prisoners when they lived. In the Christmas Carol story, Jacob Marley wore chains due his sins. But the nature, god or what ever can't punish humans since it made them with both good sides, bad sides and the free will. So it might be to show people and scare them, not a punishment from a powerful god/nature/etc.
- Can ghosts talk like living humans or make sounds with their voice?I have no clues at this one. In some fiction they can talk normally, in others not. It's up to the authors' to decide which abilities they has in the universes.
- Do you think becoming a ghost is a punishment/negative or do you think it might be something positive with it too? (In some religion, people believes at hungry ghosts. It's a punishment according to their teaching)It's a benefit to not thinking at needs to survive. You can also go through walls, fly and move yourself very fast as a ghost. You can't die if a accident would happen when you're visiting the earth, since you're already death. So there are lesser worries about certain things and you doesn't have the same human worries. But it might be boring to not have the ability to eat, if you loves food. You can probably not eat or taste normal food that alive humans eats.

A more stereo typically ghost with the shroud/sheet appearance. ^

A Yurei, Japanese ghost. ^

How I thinks ghosts would look alike, if they existed. ^
(I don't believe at ghosts)