Never had a problem with beaks, just a couple had misaligned top and bottom beaks, but they could eat and drink ok, and were not in a beauty contest so no worries. Sometimes have funny feet though, with standing on mesh floors, but I let them heal on their own, and they are fine.
I keep my ex batts separate for a few days, to get them used to the outside world, and get their strength up. Although, they can hold their corner against other hens, and are not shrinking violets. Don't put them with cockerels either, straight away, as they are not used to being treaded, and not got the strength to cope with the boys constantly at them.
They are definitel rewarding, so trusting and friendly - thats the problem, no fear of anything. Only thing is, they sometimes need getting in their shed at night at first, and will lay where the fancy, until they realise whats what.
There is no guarantee as to how long they live, and their egg production too - but at the farms they have to lay a minimum of 6 eggs per week, so thats why they are ridded. Six eggs per hen per week is adequate for most people I would say. In fact, one every other day is good, although ours do seem to lay every day once the nicer weather is here.