Hi there, I believe you can track when a document is downloaded in the system activity - see here for more on that. Then you can see when a document was downloaded in any project alongside when the status changed, etc. If you want to collect many times documents were downloaded and not go into each project individually, you can create a journal entry report that filters to Change Type = Download and add any other filters necessary (timeframe, download made by, etc.). More on journal entry reports here.
Native email notifications can be opted into/out of for when someone is assigned to a task/issue but you can also set up reminder notifications to remind them X amount of time before a task is due. More on that here.
If this helped you, please mark correct to help others : )