LEED NC 2009 Group Certification

Our project consists of two buildings on a shared site, to be built in two phases. The first building consists of an underground level of parking, one level of shell space, and two levels of multi-family residential. The second has two underground levels of parking and five levels of multi-family residential. We would like to certify the two buildings under one certification as a group and are assuming the following based on basic research: -Group certification isn't a rating system unto itself, it uses whatever rating system makes sense for the project. So in our case that would be LEED NC 2009. -All LEED NC 2009 credits on the checklist apply, but some are required to be documented individually per building. -For credits not eligible for the group approach, both buildings must meet the requirements of the credit individually to earn the group certification. -Certification level will be granted for the whole project, not individual buildings. Are these assumptions correct? For group credits such as Optimize Energy Performance, is the credit documented as a weighted average of the two buildings? This is our first attempt at group certification so any extra advice or precedents to research would be much appreciated. Thank you