I've never seen buff Orpington chicks with markings on them like that. It doesn't necessarily mean they're not purebreds, but it's suspicious. I would contact the breeder with photos. Beyond that, there's not much you can do except wait to see what they're like as they grow/feather out.
Indeed! Hmong chickens weren't bred to be fast developers like Faverolles or most of the other American and European breeds, so far as I know. It's just going to take a bit of time. They are pretty.
Yes, it is a mixed breed. Of what, tough to say. It looks kind of like a Sussex but has yellow legs. Maybe a Leghorn cross? I'm just not sure but it is very pretty.
The comb has some color but it is small. I don't know, this could go either way in my opinion. It's probably going to take a couple of more weeks to tell for sure. The comb size and color are the two things to keep an eye on.
I wouldn't put much stock in behavior to judge gender at this age...
3 and 4 have a bit of wattle development, so they could be cockerels. For me these aren't mature enough to tell gender with any kind of certainty. I'd give them some more time, keeping an eye on the combs and wattles. Growth spurts in those areas in the next few weeks would most likely mean a...
The first one has a rose comb, so probably a Dominique rather than an olive egger. It looks to be a cockerel.
Polish take a long time to tell. All I can say is that so far it shows no red in the comb/wattles/face. So that's a good sign.
If the last one is cuckoo Marans x cream legbar, then it...
She looks to be in great condition despite her ordeal. I'm guessing she's over a year old, but not by much. White Plymouth Rock is as good a guess as any. She's not a Leghorn.
It's not pure black. Whether it's chocolate is another question, and I'm not sure of the answer. Hopefully a Silkie specialist will help out, but it could take time. You could also post in the genetics thread: https://www.backyardchickens.com/forums/exhibition-genetics-breeding-to-the-sop.16188/...