Salesforce configuration, reporting and connecting email

We have a simple Salesforce set up and would like to:
a) Connect data from Sales Navigator to Salesforce
b) Enable emails to be easily uploaded into notes/activities in relevant accounts / opportunities
c) Enable historical reporting, so when we can run a sales pipeline / opportunities report today or as at say last month.
d) After c) above add report on activities report during a period (i.e. changes / edits in the past month, past quarter etc.)

Considerations:
- for a) above may require set up of company domain on Salesforce, so ensuring all data is maintained. There is also one external user and they are currently set up only to see their opportunities and this needs to continue after any updates
- for b) above, we have experimented with some plug-ins that worked well for Mac's but not so for Microsoft laptops.
- I don't think historical data logging is enabled.

Thanks and looking forward to working with an experienced Salesforce consultant.