I have heard of tenderstretch too. I would have hung them, but I read in the storey's guide to sheep that you didn't need to more then 24 hours if you wanted. I'm definitely going to next year though And being rams wouldn't have made the meat for chewy?
We never hung our chickens though, I have never even heard of that.
No you don't have to hang the chicken but you let it sit in the fridge for 24 hours before cooking or freezing. It it super tough if you eat it right away or freeze it right away.