Silkies and pecking.
Yes, Silkies can be as territorial as any other bird. Plopping a brand new bird in to an established coop will make the life hell for the new bird. If the bird has no other unknown health issues the bird will not peck because Tiny is blind. I've had a blind bird, it was never pecked for any reason other than normal chicken stuff.
Get the one young bird, place it in the cage or pen (whatever your setup is) with a divider so that they can see each other. After a day remove the barrier and just keep an eye on them.
For Silkie sexing, it can be very difficult even up to a year old to be certain about the sex. Look for streamers coming off the back of the head and feathers that are more defined in the tail. That still is not a guarantee because I have a 4 month old with the streamers and no defined feathers in the tail.
Silkies may or may not roost. It appears to be what the majority of the flock does. If most roost then those that didn't have that strong of a drive to roost will or they'll just hunker down near by.
Right now I have about 60 of them with one bantam Cochin pullet. They all interact, including the Guinea keets that are in with them until they're older. They do form clicks. You will find the same group together but are still part of the whole.