1. Template management
Yes, use template project is the best may, much better than CSV import.
You'll be able to copy the whole structure of the project, with different objects (activities, milestones, meetings).
2. Project time hours vs days
What is important is to clearly define convertion from hours to day (nb hours per day), as all work data are stores in days (and so converted in hours when needed)
For "not project activities", you can manage them as specific activities on dedicate project (that can be panned on a regular basis), or activities on administrative projects (that won(t be planned).
You can also play with capacity of resources to avoid planning fulle days for them.
3. timesheet
As admin you should be able to enter real work for others.
Resource must be "assigned" to activities to enter real work.