The red slightly swollen areas around the vent sound like they have mites. Lavender oil diluted in water, about 5 ml per gallon would do, sprayed around coop, dusting area, leaned nesting boxes, a little on the chickens will take care of the mites as well as help with the irritated areas on the...
I just had a hatch that had one chick that had a similar condition and yes it was definitely intestines as well as what looked to be a liver. There was also a deep yellowy brown liquid I believe was the yolk, it had ruptured and although the chick was strong enough to hatch naturally, it's crop...
I have looked at hundreds of pictures and spoken with the hatchery they were purchased from. I have two of them the only difference being that one has green tail feathers while the other has grey. large pea combs, black feet but pink skin, small white ear tufts. Patches of deep rust on shoulders...