As soon as it's formally announced, It moves to the price they agreed to sell for, and then you can either sell them on the open market for that price, or hold them and convert them to shares of the company acquiring. There may be a tax benefit to you doing one or the other, so I'd consult a tax advisor.

Personally, I lost a shitload of money on HashiCorp. I've "emotionally bought" 2 stocks in my life and Hashi is one of them. I like Mitchell and Armon very much, they're actually seriously great humans, both of them, but that's an awful reason to buy a stock. If I can break even and they sell for the IPO price I'll be very pleased, but that seems impossible heh. :)

Depends on the deal, but you can look at other m&as to have rought idea.