_parent in the fields search to return more than the "id"

is it possible to return more information about the parent in the
child. Just limiting to the "id" information alone seems to less
useful.

I am trying to do something like this.

I am modeling opportunities which are related to customers. So what i
want to do is, whenever i query for opportunities, i would like to get
more information about the customer data in the opportunity search
list (like name and address etc).

Also, another question with respect to parent/child. Is the mapping
that related parent - child relations, the name "_parent" - is this
something predefined and hardwired in the code or can i defined any
name for this relation. I am trying to do more like associations in my
use case, so that i can have opportunities associated to customers and
also opportunities associated with users who deals with them.

I wanted to defined the metadata with multiple association to
different types and publish opportunities against these associations.
How can i achieve this ?