Taxes on Equity Compensation

Forgive the throw away, but I am in the middle of this now

I purchased a domain for my business 10 years ago

The domain cost $500,000

The business did well for a while, but eventually died

Someone just offered to buy the domain

The offer is $1 million

But he is offering $1 million in preferred stock in a new company as if I was an investor.

He says that the company is worth $10 million

So I would be getting 10% ownership of the company - no cash.

Do I have to pay taxes on this or can I wait until the stock is public or the company if acquired?

Should I ask for stock option instead?

How do I ensure I do not lose the domain?

Should I lease it for X years with option to buy to ensure if the company goes bankrupt it would not be seen as an asset? Would leasing affect my taxes?

Thank you