How to best manage 1 iTunes account with SEVERAL devices in our family.
You can use a shared Apple ID for the iTunes, and app store purchases. Yes, you can select which apps sync to different devices


  To sync downloaded apps to iPod touch, iPhone, or iPad: Connect your
  iPod touch, iPhone, or iPad to your computer.
  
  In iTunes, select your device (below Devices), and then click the Apps
  button.
  
  Select Sync Apps, and then select the apps you want to sync.


You can create a unique Apple ID to use that for syncing contacts and calendars via iCloud. You can also sync contacts and calendars from an Exchange Server (or Google). Assuming you don't share your Mac account across the entire family, you can also just opt to sync contacts and calendars locally. 

You may find the Macworld article All about iCloud: Common signup scenarios to be useful.