I feel a bit conflicted about ex-comercial hens..
They have had very rough lives and I like to see them adjust to a nice low stress free range lifestyle. However, I think they are bred to be high output and I find they are quite short lived, compared to traditional breeds. I'd say that sometimes they can last up to 5yrs old, but most of mine tend to have strokes within a couple of years. My cross bred hens lay a lot less, but the oldest I had was 10yrs old. People seem to think that they stop laying which is why they are no longer comercially viable. This isn't really the main factor and many will lay a lot of eggs for a lot longer! As the birds age the quality of the egg deteriates, you can have thin shells that break easily in the nest boxes, its a real pain as it encourages egg eating. I have one at the moment laying thin shells and every day I find a broken egg in the next boxes.
For a first time hen keeper, why not go for a more traditional breed I think they might be more rewarding? Good luck whatever you decide to do though, hens are wonderful to have around and you really can't beat fresh, hope produced free range eggs