Basically, I was a software developer at a company and I was issued some stock options early on, before the company grew significantly. The company then hired a CEO who pledged to take the company public, eventually. This never happened and eventually I left the company to work for other companies. Before leaving though, I paid money to exercise my stocks and I now have a stock certificate for a (probably very small) portion of a quite successful private company.

I have spoken with some other former employees and some of them have had trouble selling any of their shares (after leaving the company) because the company is private and they left on not-so-amicable terms with the company. I personally left the company on good terms but most of the people who knew me well are now gone from the company. The terms of the issuance of the shares require the company to approve any sale of the shares to another entity. My questions are threefold:

1. Are private companies in Delaware, USA required to facilitate the sale of the shares of the company or could my shares be just as valuable as toilet paper, if the company never goes public? (Assuming that the company doesn't want me to be able to get rid of my shares).
2. My colleagues who previously tried to sell their shares wanted to know how many shares were issued and what the most recent valuation of the company was at that time. Apparently the company refused to give them this information without making them sign an NDA. Is this legal? How could someone be expected to go about finding a broker to sell their shares if they have signed something saying they will not disclose the information that would allow a buyer to know the approximate worth of the shares?
3. Should I approach the company in some particular way, asking if they could facilitate the sale of my shares to other shareholders? If I do this tactfully, perhaps I can be in their "good graces" and therefore be more likely to be able to sell my shares, than my colleagues who have failed to do so before me. Any tips? Since my rough approximate value of my shares is not very large (probably less than $20k), I don't think it is worth hiring a lawyer because the company ultimately has better lawyers than I could afford and I don't want to put money down to hire a lawyer and then have a high change of having nothing to show for it in the end.