HI and welcome to the forum

I'm fairly new to chickens, but with my limited experience - here goes !
Feeder and drinker
Worming medicine
Mite/louse powder
Oyster shell and grit
Cider vinegar (for adding to their water, but can only use in plastic drinkers)
sawdust & straw for bedding
Layers pellets and mixed corn.
I'm sure there will be other things I've forgotten but more experience folk will keep you right

If your run suggests 3-4 chickens, I'd probably start with 2 in there and see how you get on - you'll maybe find you have to move it quite regularly if it's on grass/earth cause they do a LOT of scratching about. Our 2 have a 6ft by 6ft run and I feel as if I'd like it to be (at least) twice that size !
I have a warren and a rhode island red - the warren LOVES cudles, but the RIR is a bit more stand offish ! I inherited these ones, but if I was choosing more, like Gavo says I'd go for ones I liked looking at. Don't get me wrong, I love my wee chookies, but there are lots of very pretty breeds out there.
Good luck and lets us know how you get on !