I butchered a single rooster last year. It was my first (and only) experience butchering of any sort. From start to finish it took about 90 minutes, most of that involved plucking (or reheating water so we could scald properly -- I think I had the temperature wrong and/or didn't leave in the water long enough). My kids who were 10 and 12 at the time participated in everything except for the axe wielding.
Butchering 3 or 4 would not have taken us much longer. And, I am sure that it will go much faster next time around.
This rooster was about one year old. The next day, before putting him in the crock pot, I cut off a piece of meat and fried it. It was tough, but quite tasty. My son described it as "tastes like chicken, only chickenier".
I had some 17 week old roosters processed last fall. I have stewed them all. They make wonderful stock and great chicken pie, chicken and dumpling, and chicken soup.
I do not mean to sound preachy at all, but I think experiencing home butchering was beneficial to both me and my kids. You and your kids may have a different reaction to the process, you're in a much better position to know about that than anyone here.
Tim
PS The pullets will likely have less meat than the roosters and you can probably sell each hen for the price of a Purdue roaster in the local supermarket.