Been through an acquisition on the other end.

My main piece of advice is to talk to the employees of the larger company to suss out whether they like the company culture, whether you can or want to work with them and the processes your company will inherit. Treat it as an unofficial low-stress way of interviewing a company. :)

It's pretty much a given rule that the culture of the smaller company is subsumed into the large one - the only question is how fast it happens.