Thank you for your answers.
Also have a question concerning promotion schemes, is it perspective enough to promote it in social media? Of course, those who are interested may find it anyway.
And will be there any entry requirements, for example providing user's private information or verifying is an optional procedure?
Right now we have a pretty restrained promotion budget (it's one of the reasons we're doing a presale in the first place), so social networks are among the best instruments to get coverage, considering our resources.
Although it is encouraged for Experts and Authors, identity verification is entirely optional.