If I have a single room can I have guests?

Yes, I think one would be allowed

You may have to pay for the guest if its a single room. If you paid for a double room, and you were going alone, you could have someone.

Sure.

I think so

Yes 1 person. Additional charge for more.

Up to 2 guests. There is an additional charge for more guests.

Yes at least one person

I did. I got a single and had 2 guests. But we were quite and no one ever knew. I dont think it is allowed though. LOL

I doubted