To eat: Layers pellets and/or mixed corn. Oyster shell (for the calcium, they need it for forming egg shells). Grit to help grind their food up. A food 'hopper' and something for fresh water, hens drink quite a lot. All this is available from pet shops/country stores/feed merchants or online. If you keep the food in a metal or plastic dustbin, it'll stop rats/mice etc eating it. Chickens also like & need greens so either bung them some grass or supply them with broccoli/cabbage/whatever.
They'll need straw for their nest boxes (where they lay their eggs) and newspaper/sand/woodshavings on the floor of their house. They need cleaning out about once a week but it doesn't take long. I'd get your DH to look at the shape of hen houses on an online store (try looking at flytesofancy or P&T Poultry) so he knows what to build.
If they free-range during the day there is always the possibility that the fox will get them, cats are most unlikely to bother with a full sized chicken. We had totally free-range hens for 4 years before the fox turned up (then we lost 3 flocks in as many weeks). The run needs to be as secure as possible with either very high sides or a roof, both to stop chickens flying/jumping out and foxes jumping in - if you don't have a roof, the fence needs to be at least 6ft high (ours is 10ft). And something to stop the foxes digging in - such as putting the run on slabs or surround it with slabs or cover the bottom of the run with chicken wire or better still, wire mesh. Or electric netting.
Chickens need worming twice a year - this only means mixing Flubenvet powder into their food for about a week.
A cat litter tray full of sand will give them somewhere to dust bathe. You can shake some mite powder into it from time to time to keep the bugs at bay.
Does this sound a lot? They're really not much bother once your up and running.