As you don't have a flock, and it would nearly be impossible to quarantine 5 different birds, take a good look at them before you bring them home. Open up their wings, and look in the arm pit, for any bugs. They should look perky, clean and shiny. They should be interested in their surroundings. They should have good feet, and legs.
At 5 months their combs may not be real red, but the should be plump.
Even with a careful examination, you might bring in a sick one. It is a bit of a gamble. But for most people it is the established flock that they want to protect from bringing in disease. As you do not have an established flock, I would go for bringing them all home and putting them all together. Do put some boxes, or perches in your run so that there are some different levels and hiding spots, till the pecking order gets sorted.
I have a mixed flock and love it. It does make them easier to tell apart, which is kind of nice for a new chicken owner, after a while, you can tell chickens apart even with the same feather pattern, but at first it makes them easy to get to know.
Red stars are good layers, my buff orpington went broody for me, which is something that I wanted. I had a barred rock and liked her quite well.
If you have small children I would not get a rooster at all. In fact it might be best if you just got the hens and played with that part of the project for a while, till you get a little experience. Roosters can be good, or the can be horrible. I have had chickens for 4 years, and I am just now starting with the roo's.
MrsK