No, you do not have to sign in to contribute to WikiAnswers. In fact, you don't even have to register to ask or answer questions. However, there are some functions that are reserved for registered (and signed-in) users that are no accessible by unregistered users.
You don't have to login it is not mandatory.
Yes, you do. A valid email address is a mandatory requirement to sign in to WikiAnswers. You can opt to be a guest - and ask or answer questions without an account - but registering helps you reap the full benefits of the community.
No, you do not have to be 18 to answer questions on WikiAnswers. In fact, you can be any age and still be allowed to answer a question on WikiAnswers. There is no age limit to sign up for an account and contribute to WikiAnswers, but there is an age limit to join a program.
To show your love for WikiAnswers, just contribute. The more you contribute, the more it shows that you love WikiAnswers.
It is extremely easy to contribute to WikiAnswers. There are big ask and answer bars to answer and ask questions, and pretty much everything you need to contribute it laid out before you on WikiAnswers.
No, there isn't a subscription fee to join WikiAnswers. All memberships with WikiAnswers are 100% free, no charge whatsoever. It only costs a little bit of your time to sign up and contribute to WikiAnswers, no payment. Plus, you don't 'subscribe' to WikiAnswers - you join the website with a membership.
To encourage people to contribute on WikiAnswers.
You can become a member, or answer an unanswered question in wikianswers
It is perfectly safe to sign up for WikiAnswers.
Start an account.
Certainly. WikiAnswers welcomes people of ANY nationality.
Yep, you can message people. But you also have to contribute to WikiAnswers, not just chat.