Good quality feed...fresh water...poultry grit....good bedding (shavings or shredded straw) with added lice/mite treatment powder is the very basics. If they get little bit greens each day (or even some berries) that is bonus that will keep their life that little bit more interesting, will help them keep healthier and will give you better eggs
Any wheat/corn based feed is better to leave to later on the year when they will need it for extra energy for keeping warm.
Snails are good source of protein that they will gladly eat, though need to help them by crushing the shells first....the only issue with their delicacy is that you need to keep chicken's worming updated...which is not bad thing to do even without snails in their diet...many different options are available.
If possible, keep feeders elevated from the ground..it will help keeping rodents away..chickens will scatter less feed and there is less food loss.
Even the sun is good for them...they will need some shady area too.
Dust baths...they like to keep themselves 'clean' and it is their part of their natural behaviour. If you can make them tray or let them have some corner in pen where you can put some sand (with added wood ash and/or lousepowder or similar)..they will gladly roll around in it and get themselves truly covered..
One next box between 3 girls would do but 2 would be even better...again, keep clean bedding there with some 'powder' at the bottom of the box will keep girls happy.
Perch(es) to climb on and roost..indoors and outdoors will give them place to nap, 'play' or just sit down and watch the world go by.
OH...and don't forget to
talk to them...A LOT!...they will soon start talking to you too and chicken keeping become that little bit more interesting and easier when you can pick their moods and needs by the sounds they make