I also got mixed pullets from TSC a couple of weeks ago...the red ones with the stripes are Golden Comets. The white/yellow ones look like they are going to turn out to be Cornish X. Our TSC got them from Privett Hatcheries if that helps.
About your chicks, I wouldn't medicate them unless they are sick. And to post a new topic go to any one of the forum sections (like Raising Baby Chicks) and in the main part of the section where you can see all the topics, there's a button toward the upper right hand corner that says "Post New Topic". Click on that and there ya go.