What do you mean by development? What it will take 4 years, and why do you think that this will be so long?
Can we use and sell / buy tokens?
You can sell, buy or spend tokens after 45 days after ICO (if you are not USA citizen) and 12 months later (if you are from the USA).
Before you buy and sell tokens, you need to get a listing on some stock exchange. And there was no news about it yet. So ... I don't even know, it seems to me too early to discuss the sale of tokens)