I'm new at the chicken thing, but mine learned to come when I came out the door cause they thought if they came and begged me, I would treat them, and they're right!!!
About the wing clipping thing, I don't know what the right thing to do is, but mine free range and when I got them (as adults, I saved them) they had their wings cut, but were not free ranging birds. I personally feel that they should have full function of their flight in order to better escape attack should that occur. Sometimes flying into a tree to avoid a predetor could/would save their lives. Therefore I'm allowing their flight feathers grow back in.
Just my opinion. Hope it helps.
Edited because I'm not sure I explained well enough, they were not free ranging birds when I got them, but like you I kept them in their coop for roughly two weeks to get used to me, and then let them out in the morning one day. I hung outside all day to watch them and make sure they stayed where I wanted them to, they did, and as the sun started to set, they came to the door of the coop, groomed theirselves and eventually went in for the night. That's how it's been ever since. I think you'll find that they will come in every night.