I'm setting up several child domains in an existing Active Directory forest and I'm looking for some conventional wisdom/best practice guidance for configuring both DNS client settings on the child domain controllers and for the DNS zone replication scope.

Assuming a single domain controller in each domain and assuming that each DC is also the DNS server for the domain (for simplicity's sake) should the child domain controller point to itself for DNS only or should it point to some combination (primary VS. secondary) of itself and the DNS server in the parent or root domain? If a parent>child>grandchild domain hierarchy exists (with a contiguous DNS namespace) how should DNS be configured on the grandchild DC?

Regarding the DNS zone replication scope, if storing each domain's DNS zone on all DNS servers in the domain then I'm assuming a DNS delegation from the parent to the child needs to exist and that a forwarder from the child to the parent needs to exist. With a parent>child>grandchild domain hierarchy then does each child forward to the direct parent for the direct parent's zone or to the root zone? Does the delegation occur at the direct parent zone or from the root zone?

If storing all DNS zones on all DNS servers in the forest does it make the above questions regarding the replication scope moot? Does the replication scope have some bearing on the DNS client settings on each DC?