As a guest: Accepting food, drink and help:

Thank you. That's very kind of you.

As a guest: Travel small talk.

How far is it to the office?

Moving from small talk to talking about business:

So, do you travel much for work?

Are you working on anything interesting at the moment?

What's happening in your sector / industry right now?

Changing the topic:

Actually, we're working on an interesting project right now.

By the way, my company is working on an interesting project right now.

Funny you should say that, I'm working on...

Speaking of copyright, do you know anyone who could advise us?

That reminds me, I think I heard that your company is...