Hi @vani1012
For the question - We would need a list of people with DAM access.
It totally depends on the way the user permission model is setup as the permissions can be granted to the granual level as well as the parent level.
i.e. the Dam permission can be granted at /content/dam or the folders within it /content/dam/<project-name>.
Depending on the way it is implemented you can created one custom servlet which check for the acl nodes and create a list and return it.
Another way could be that the users are part of the group "dam-users". If that is the case you can directly check the user after navigating to the path
https://<host>:<port>/ui#/aem/libs/granite/security/content/v2/groupeditor.html/home/groups/d/<group-id>

Other question - people who have created or edited pages or uploaded assets.
For this the only way I could think is create the custom logic to iterate the paths and read the properties and create the list/map for the people belong to the key i.e. created/uploaded or edited based on the properties i.e. jcr:createdBy, cq:lastModifiedBy respectively.
Thanks,
Shailesh