Record Merging - Secondary Record

Hi,

What happens to the activity data/log  (form fills, emails, link clicks, opt out etc.) on all the merged/secondary records? I have read through the documentation (https://nation.marketo.com/t5/Knowledgebase/Understanding-Merges-in-Marketo/ta-p/249697) and (https://docs.marketo.com/display/public/DOCS/Find+and+Merge+Duplicate+People) but there is no specific reference to the secondary records. 

Also, what happens to the leads/contacts in SFDC for all the merged/secondary records?