Very good pdf for 8677 chassis.

ftp://ftp.software.ibm.com/systems/support/system_x_pdf/8677_planning.pdf

Also in my research I have realized that you DO NOT need a new power domain if you are on;y adding new switch modules. 

However if you are using ANYTHING in bays 7-14 then you will need to add a new powerdomain(new power supplies).

Also ethernet goes in 1 &2 and

fiber goes in 3&4.