Size of mattress in soft sleeper and luxury

Hello
Could you tell me what is the thickness size of the mattress (5 centimers) compare to luxury mattress ?

Could I book 4 beds (bunks) in a full compartment as we are 4 ? And an other close to the first one for 3 people ?
(Means 7 bunks) ?

What is you fees for 7 people for same travel and train ?

Thanks