From my experience with chicks and turkey poults has just been the feed, turkeys especially the board breasted ones need the higher protein. The only other thing is to make sure that they have sure footing in the brooder. I use hardware clothe cover with pine shavings to keep them from sliding...
I just received my latest 8 chicks from My Pet Chicken and only have one which had some travel stress. The wife and I have been giving it some Save A Chick by dropper and it is coming around and eating and drinking. This was my first to gets chicks mail order and I had the same fear that you...
They should be fine as long as they have some place that is block from the wind and rain. Turkeys make great mother hens for any other fowl. And that sounds great that it is acting like a big brother/sister. I getting ready to get some more chicks and they are about 3 to 4 weeks old I'll place...
Looks like a Bronze turkey about 3 weeks old. Give some higher protein feed like turkey starter that has 30% protein. It should not be aggressive to younger birds I would watch out for older birds around it.