Weasels kill just like that. Once the get excited they will kill over and over again. They also sometimes pile the birds up. They are blood thirsty devils..so sorry for your loss. A night like that can be devistating.
Depends on the breed but you should be getting an egg any day now. Just keep an eye out and be patient..look around on the ground, sometimes the first egg or two will be layed in the corner of the coop. Oh and the first few eggs will be pretty small and will increase in size in the weeks after...
I have raised Australorps for years and they are one of my favorite breeds. They tame easily, are great layers and all and all are very pretty birds. I saw where some had said they were a bit flighty but that has not been my experience at all. My experience with them is that they stand...
For the most part they are on their own, when it comes to becoming broody. This year I have been having fits with TOO MANY broodies. Even my Seabrights are trying to set. The breed other than a silkie that has been most reliable/predictable is bantam cochins. They go broody several times a year...
I would try putting a few objects in the coop/run for the new birds to hide behind and stay out of sight out of mind. They have to work out a pecking order and every time you separate them it all starts over when you put them together again.
Another thing you may want to try is putting a wire...
I have raised quite a few blue cochins and always keep a few on the lot for no other reason than they are so dang pretty. Cochins in general are not the best layers though..usually medium to small eggs at a rate of about 3 a week. Maybe 4 a week if she is feeling friskey.
The best tip that I can give you is this...you mentioned that you have 20 acres...GET MORE CHICKENS!!! 4 or 5 is not nearly enough with your space! I have 6 acres and I have around 120 birds but I do have a nice sized barn with a 20x40 lean to on the side. I completely enclosed it with wire...