garbage with data integrity check

Hi,

NBU 7.6 remove crcollect and uses clean of garbage through data integrity check (enable/disable in contentrouter or spa). I am lookup for information about process of the data integrity planning and schedulling. 

Manually start data integrity check ?

Sheduling data integrity check   ?

When is the DICH started ?

How long time these deleted images (bpexpdate + nbdelete) will remain in MSDP as garbage images, by default ? 

Many thanks, Petr