(a) You need a lawyer who deals with this kind of stuff regularly and has a realistic and well-informed view of what the outcomes are going to be. Most lawyers aren't like this.
(b) Legal gets expensive very fast, especially as it transitions from advice to negotiation and document review. At this scale of opportunity (the way the company is described), I'd stick to get getting advice!
(c) Past the "can I be fired" question, which I agree is urgent (and probably predictable), a lot of the negotiation here isn't going to be about the law so much as it's going to be about what both sides are willing to accept. If you have friends who have been in founder disputes like this, their input is going to be just as valuable as the lawyer's.