1 - If you're in a risky business and your income may be volatile, I think your emergency fund needs to be what'll help you sleep at night. That being said, your typical e-fund usually is 3-6 months worth of expenses, and $50k seems a bit high for that. Does your DH work, and is his income more secure? If he does and it is, I'd reckon you could lower that a little. But again, that's just my opinion, and you should do what your comfortable with.
2 - 50k seems like a great down payment amount (heck, you could get a nice little condo for just about that price in some areas!). You say getting into real estate is more of a want than a need - what makes you say that? Do you have any other pressing goals? Everything for you baby set up (congrats by the way!). You didn't mention any outstanding debts, but if you have a mortgage, student loan, etc., you might want to allocate some of that money there instead.
3 - If this money is strictly business related, I wouldn't touch it, not for your personal finances at least. Is there anyway you could use that money to gain more clients, make your income less variable, etc.? If not, I'd leave it be.