Point 5: If and when you get the site back, get yeomanry.
As you can see there are four hearths. Making an individual claim here would prevent others in my group from getting in and out. We're working on getting a village claim, but it takes time.
Not necessarily.
For future reference, When you make a claim, you can allow kin on it. So you could have kinned the people in your group and let them on your claim. Then they're allowed access.

Typically, the general consensus in this game is "if it isn't claimed, it's up for grabs." or, "finders keepers, losers weepers."
So, sorry that this happened to you. (Not sorry, as in "I did it an regret it" but sorry as in "shit sux, and sux that it happened to you." )
Talk to the dude, maybe you can get your stuff back. Or, he'll lol in your face. But it's still worth a shot.