memberOf Overlay

I'm a little confused with implementing the memberOf overlay. I've seen some articles talk about the slapd.conf file; others are talking about an ldif file, etc. Two questions keep coming to my head everytime.

I have an Ubuntu box with OpenLDAP installed via apt-get. I need to utilize the memberOf attribute.

1) Based on my installation method (OpenLDAP from apt-get), what is the suggested method to use to obtain the memberOf functionality?

2) Will I need to create an LDIF file for every group I have or create in the future? Is there something I could do in the schema to always include the memberOf in the every user I create for any group?

--TR