I'm not going to mention the guineas, cause I have absolutely no experience with them
. But otherwise, it shouldn't be too difficult....
Integrating chicks really isn't near as big a deal as with older birds. Chicks' social structure is still being established, they don't have positions to defend like mature birds do.
Move your 4+ week chicks to the coop now. You may or may not need to run a heat lamp out there to run at night for a week or so, depending on your weather.
When you get your older chicks, just put them in with the chicks in the coop. They're all babies, integration isn't a big thing as with older birds. Sounds like you have a decent amount of space, and put up some hiding places for littles to get away from any more aggressive chicks and you should be good to go.
Hatcheries sell either day old chicks, or point of lay pullets. You're not going to get a month old chick from a hatchery. You'll know if you ordered a started pullet (around 5 month) by the price and lack of selection on breed. So, assume you're getting day olds. Brood them until they're 4+ weeks, then put them in the coop. The run should be done by then, and again have hiding places.
You are going to have to do some construction, though. Even not counting the guineas, you've got 28 birds. Your coop is less than half as large as you're going to need for that many adult birds. Your run is going to have to be around 400 square feet, once you toss in those guineas.
Have you talked to Ideal to see if they're sending extra males for warmth? Even though it's warmer outside, with only 10 chicks in an order you're likely to get several packing peanut males, if they're sending those you'll need to have a plan for them, also.