I do have a contract with many pages of legal details covering definitions and contingencies, but not what I'm really interested in which is, what do I get at valuation $X.

Based on the $, I guess you are in the US, but in which state is your company registered? Every state has different laws that protect minority shareholders. Often, as minority shareholder, you are protected by law and you rarely have to sell your shares, if you don't want to. BUT as the legal system goes - and it is very complex in the US - there are more exceptions and loopholes than there are rules. You need to know your share agreement and all provisions as well as your state's law. Depending on the state and the form of the acquisition, certain states like Delaware and Texas allow it that minority shareholders can be forced out of the company (https://smallbusiness.chron.com/force-shareholder-sell-stock...).

Normally, you should first talk to the majority shareholders. Then talk to management, because they only act on behalf of the majority shareholder (I assume they are the same in your case). You could mention that it is your right to know. If they are still not transparent, try talking to a lawyer or somebody that you know has a similar contract in the same state and industry as you.

FYI: I am not a lawyer and this is no legal advice :)

It should be valuation divided by all shares equals value per share.

The tricky part is whether the valuation number you have is what the company is paying to buy your company or if it's the overall value. If it's the overall value, then you need to subtract your company's outstanding liabilities.