Not strange at all, I did try to get this last batch into eating things besides just chick food. It eventually did happen but it was around two weeks before they showed intrest in variety at all. Slow learners or maybe just picky I really don't know.
I just feed the 20% for three months then switch to grower.Twenty pounds should do just fine. They'll need grit if you feed them anything other than chick starter. And they need to stay inside until they have real feathers. :)