Using someone else's account without their knowledge and consent is an abuse. It's possible that if you're caught doing so, you can be brought up on criminal and civil charges in court.
Yes. Ideally your own.
Yes!
Yes, you need a Yahoo account to use Yahoo Messenger.
Yes you do, And you must be at least 13 to use it. (You can be any age for a Yahoo Account)
You can switch from Yahoo account to Gmail account easily. The account can be created on Gmail account. You can export all the data from yahoo account as well.
You have to create an Facebook account,with yahoo,gmail,or mail.ru account with secure pass word .Also, you can use Wikipedia as homework and yahoo answers.
There are a lot of websites that use Yahoo ID's such as: Flickr, Yahoo Answers, Delicious, MyBlogLog and others.
Yes, you need to have a yahoo account to join yahoo answers.
use three emails
Yes to get an Zynga account you just need any email id so you can use yahoo mail also.
Google & Yahoo are in the same account, so if you get a yahoo account you will also have a google account. :]
She doesn't have a yahoo account!
You'd have to know their password and email. But I advise you not to try that.