Confused: Associating a device or computer to your Apple ID

Our family has 4 Macs, 5 iPhones and 3 iPads. (12 devices) All these devices make use of the same Apple ID when purchase of apps/books/music and iCloud sync concerned.

Now I am utterly confused after reading the following tech article: http://support.apple.com/kb/HT4627

"When you turn on Automatic Downloads or download past purchases on an iOS device or computer, your device or computer will be associated with your Apple ID. Your Apple ID can have up to 10 devices and computers (combined) associated with it."

1) On all our 3 iPads and 5 iPhones, "Automatic Downloads" is completely disabled during the last months. Only on the 4 Macs, "Automatic Downloads" is enabled for Apps only.

- Now I wonder if there is any co-relation between our 12 devices and the total of 10 max which van be read on above support article ?

2) If I open iTunes/Acount/Manage Devices/ I see still some of the above iPads and iPhones listed with a date of more than 3 months ago.

- Can I delete these listed iPads/iPhones (date > 3 months ago) without doing anything harm to app purchases ?

- If I delete these listed iPads/iPhones (date > 3 months ago), can I still sync with these devices ?

- only 3 out of 4 Macs are listed. All have "Automatic Downloads" for Apps enabled, so where is number 4 ?

Thanks for your help 🙂