Novice configuration help needed - openVPN

Just got a Turris; don’t know much about networking.
Questions to start:

  1. Can I control what traffic goes through VPN and which does not ? How?
  2. What should be in the configuration field for client name? A specific user ? A specific device ? A specific IP address ? Does this refer to remote client ?
  3. How and from where do I control the blocking of traffic from / to specific IPs (I guess that would be the IP blacklist) ?
  4. First thing I did with openVPN was to get a CA. Where is that stored ? What ensures it is secure ?
  5. Configured OpenVPN in foris, added a window client name for my win10 device but when I try to go to openVPN address (https://someip:1194) - “can’t establish connection”. How to test from my mini-pc?
  6. Given that I am novice at networking where can I get up to speed on this. I am looking at your doc pages, but maybe my questions are too basic; I cannot find answers I need.

Many thanks,