Nest Box and Roost?

[mylilchix]

I have langshan, faverolle, EE, RIR, australorp, brahma, and cochin. How high should I hang their nesting boxes? I was planning on building 8, 2 tiers of 4. I'm also wondering how high I should go with roosts and how far apart to space them? I want to make things comfortable for my heavier breeds.
Thanks,
Sonja

 

[Chickaroo!]

I know the nest boxes should be pretty much no more then 18" off the ground. I know this because I posted pics of the beginning of my new coop and apparently had the boxes hung to high and several people on here were nice enough to tell me!
Roost, ??
I choose to have a ladder style roost and no one said anything about that in the pics so I guess as high as you want them?