Everything you do on the company laptop can and will be monitored. As a rule, I never do anything of a personal nature on company equipment.
As far as exit interviews go, don't do one. You are under no legal obligation to do an exit interview. Just politely decline if you are asked by HR. You might think this is your opportunity to tell them how sh---y your manager was, and how terrible this or that process is. You will be wasting your time. Nothing will change. All it will do is brand you as a malcontent and put you on the Do Not Rehire list.
If you decide to do an exit interview the smartest way to play it is to say that everything was wonderful and that you are grateful for the opportunity to have worked there. Lie through your teeth if you have to but don't say anything negative. You have nothing to gain and everything to lose.
If a future employer contacts them for a reference, legally they are only supposed to disclose your position and when you worked there. But how will you know if they disclose any negative comments you made on the way out? I'm not saying that would happen but it could and you would never know, other than your new job offer gets rescinded.
So why take the chance? Play it smart and either don't do an exit interview, or if you do, say nothing but nice things. The first step on winning the game is knowing how it is played.