Hire a reputable lawyer that can look over your stock purchase and employee agreements as well as give you general counsel on the situation. There are so many variables that it's really tough to answer your questions specifically. That being said most acquihires that I've seen tend to be for the team itself and not the product. It's a straightforward way for a company to buy a talented engineering team that's already worked together.
Depending on things like board control, voting rights, how the seed round was structured, etc. will determine most of the answers you are looking for. The term founder doesn't have a lot of legal meaning and if you have a sizable amount of equity in say restricted stock, that's what most people would call a founder. Something else to find out is your vesting schedule and what your triggers are for acceleration. Unfortunately if there are investors there is probably a clause that they get paid back first and acquihires aren't usually lucrative amounts but again it depends on all the specifics.
Depending on things like board control, voting rights, how the seed round was structured, etc. will determine most of the answers you are looking for. The term founder doesn't have a lot of legal meaning and if you have a sizable amount of equity in say restricted stock, that's what most people would call a founder. Something else to find out is your vesting schedule and what your triggers are for acceleration. Unfortunately if there are investors there is probably a clause that they get paid back first and acquihires aren't usually lucrative amounts but again it depends on all the specifics.