Do you really want to join a company after only 3 hours of conversations? Which company you join will have a huge impact on your future. You should do your due diligence as much as the hiring company does. Do I really want to spend the next few years of my life working alongside those people? When we were a small startup (10-20 people), we'd take candidates who we are making offers to for dinner. It's not quite an in…
Right on! The more conversations with individuals in the organization actually works in your favor. You'll be able to compare and contrast priorities, vision, work flows, etc... Getting team buy-in is an important consideration for managers.
If the time commitment is a real issue for you-- share that with them. See if they're amenable to a Skype/phone conversation instead.