Good luck. Chicken math was part of our down fall at our last house, we had intended on staying in Missouri for a long time but then life changes and so we picked up our roots and are moving on. I built our last coop based on a simple plan, that my DW agreed to, essentially the plan was to keep 2 - 3 chickens per year once we started, since there is just the two of us. So first year we would have 2 or 3 hens, second year 4 - 5, third 6-7 that way we kept our flock fresh and younger. Well by the end of the first year we had 10 hens and by mid summer of year two another 5, with one rooster. The coop we had built was big enough to keep them all as they only slept in there, we had a 20' x 20' run, and let them free range almost everyday as well. Now that we are moving on the next coop will be easily expandable as I am simply starting out with a 20 x 30 carport which will allow us to separate hens, birds raised only for the freezer, and rabbits. Hopefully we will have plenty of room for chicken math with that.
I am sure you have read plenty of posts on here regarding chick care but some things we have found to be true. We have kept ours in the garage when until they feather out during late spring. Our first chicks we picked up though was in January so we kept them in the garage almost 6 weeks with the last couple of weeks slowly exposing them to the cold to encourage more feather growth. Keep them warm, dry, fed, and watered. The first day offer them warm water and dip their beaks, let them go and ensure they drink (once you get their beak wet they should tilt their head back and consume the water). Red heat lamps discourages picking on others especially if they get an injury. Check them all for pasty butt - its easy to recognize - there will be a lot of poop crusted on their back side. It is usually easy to remedy - and must be remedied if you want the chick to live - get a bowl of warm water and put its butt in the water then slowly work the crusty's off, then dry the young lady off so she doesn't get cold and so the others won't pick on her wet feathers. We have found that the chicks we handle the most learn to like us more, are much more friendly and like to be picked up. You may loose some - not all chicks are going to make it - that being said out of all of the chicks that we had the last couple of years we only lost 1 and it really was a runt and we probably should not have taken it.
As much as I want to raise our hens completely "organic" I do cheap at the beginning by feeding them the medicated starter feed for the first couple of weeks to alleviate illnesses. With those starter feeds as well you do not need to introduce grit to them as it is built into the feed.
The litter you use the first couple of weeks is important as well - do no use newspaper as they will develop leg problems - we only use pine shavings (not cedar - it is harmful to chickens from what I've read on here) but I am sure there are other acceptable litters available.
Clean Food, Clean Water, Warm and Dry.
Good Luck...