Typically the "entire database" is turned on in the beginning. When the zip code is set, there is a question if you want the full database to be on. It is also something that can be turned on via Sentinel when editing a profile (check hte Monitor Full Database box in Scan Selection tab.
As folks become more advanced in their scanning, they might create one or more Favorites Lists. These Favorites Lists would contain systems, frequencies, etc. that are of interest to them.
A Favorites List will have an option for Location Control. When Location Control is On, the systems, frequencies, etc. in the Favorites Lists are "activated" when the scanner is in the appropriate area. (As noted above, a GPS device tells the scanner where it is so this Location Control feature will function.)
However, a Favorite List can be active regardless of the scanner's location. This would be Location Control Off.
It is your choice.
Generally if the "things" you want to monitored are in a Favorites List, turning off the full database is a better practice. Otherwise you are monitoring those things twice - once via FL and again through the full database.
My practice is this: When I'm in my home area, everything I'm interested in has been programmed into multiple Favorites Lists. Also if I'm traveling, I have a Favorites List for my destination. I'll leave the full database off and just monitor Favorites Lists.
When I'm between home and my destination, I'll turn on the full database and let my GPS and scanner work together to turn on/off things for the area I'm passing through.
You are not a pain - these are good questions for a new user.
