Required Intuit Account for TurboTax

I purchased the CD version of TurboTax Home and Business so that 3 other family members could use the product.

(1)  Since we are required to have an intuit account - will my children need access to this intuit account to install the product on their own laptops?

(2) Are each of our own tax returns kept strictly on our own computers? i.e.  Will my children be able to access or see my returns and will I be able to access theirs?

(3). Does Intuit store our returns somewhere online??  or is everything kept strictly local to each of our own computers?