If you mean the character in Zelda, his age was recently confirmed to be 9 years old (see related link).
If you meant ChildLink as in the organization, then this would depend on the country or state that it's in.
No.
18see link
see link
See link
yes, see link below
see link below
18see link
Age 18see link
See related link below.
Yes, provided they are not too old in accordance with state laws. See link
age 18 see link below
Yes, but the support can be modified to go directly to the child, or stopped. see link