What time did you go to lunge your horse at? I know the barn Rena is at closes at a certain time, and the arena is usually closed all weekend if a clinic is going on.
I personally like my horses stall with a lot of shavings in it because I've seen horses get sores on their hocks from lack of. But that's just MO.
As for the weather, that's understandable if they didn't want to bring him in, that can be a huge pain in the rear end if your doing barn chores to do that. It's hard to blanket to the weather, but I'm almost sure your horse would've been fine out in the field for a few more hours in bad weather without proper blanketing, horsesndont get cold like we do.
I would try and talk to the BO if you're upset about anything serious.
If there are no horses in heaven... im not going.