Ducks take a long time to hatch. you can make a hole if you want but it is probably not necessary. They can take up to 48 hours to hatch after they pip.
It is possible that they could be picked on, but it will be better if you do it sooner than later. The older they get the more flockish they become and don't integrate as well. Even if they tolerate each other they won't really become one flock. If they mix at a young age this is not as much of...
Chickens lay best in their first year and go down considerably after that. I usually cull around 3-4 years just because I am enjoy the chickens and don't mind if they start laying less (within reason) unless I have one that I just really like and it gets pet status and gets to live forever haha.
The only way is if you have a BR rooster. You can separate the roosters though and only have the barred rocks together so the roosters won't fight. Obviously that would mean building a shelter for them.
Unless you were to do artificial insemination or something but although possible is not...
for the 8 and 7 day olds, you shouldn't have any problems at all. They are still really small and won't have any pecking order yet.
For adding the one-day olds you need to be more careful though. The larger ones by then will be way bigger and can hog all the food. You can mix them but need to...
Day 25 is very late, and you need to analyze the incubating conditions to make sure temp and humidity were accurate and consistent. There is a good assisting guide on here that may help. Click Here
This will help you know if you should assist or not and how.
She will be fine with them while she is incubating. The issue is when the chicks go to hatch as other chickens can be difficult and hurt the chicks. It depends on how protective of a mother the hen is as well and if she can take care of them so the others don't hurt the chicks. I always separate...
You can already turn them. I would turn them tonight since they've been on one side all day. Then tomorrow start turning good. Just make sure you always do it on an odd number of times per day so they are on a different side each night.
I don't see anything alarming in your brooder set up. In fact it looks quite good. What is the temp at?
I think what is more likely is that they had just got them delivered and you unfortunately got some that didn't do well in the mail from the hatchery!
For the first bit 90 degrees is perfect. They say you can go down ten degrees for each week. I usually leave it around 90 for the first week and then drop it down to 80 or so for the few weeks after that. With enough space that they can get out of the heat like you said if they get too hot
Were they shipped eggs? That could have greatly decreased the viability of the eggs.
Good hatch rates are dependent on a number of factors.
1) Humidity is very important. If it is too high during incubation the eggs will not have enough moisture loss and the chicks will essentially suffocate...