If the kill switch is done correctly it acts as a firewall in a way and no traffic leaves the machine. This is kinda the problem with any vpn software you install. They hook into the OS at a very low level so no traffic can bypass it. Unlike the windows firewall for example even if you say every IP is blocked except some small list the ones that microsoft uses are still allowed. So using the windows firewall to prevent microsoft updates doesn't work but a third party firewall would.
The downside to client software is that some of these vpn do not uninstall correctly. I have had to reinstall windows when I was testing out different vpn client and doing what I thought was install/uninstalls. I now only use a router vpn.
No log is mostly to keep law enforcement and maybe a private lawsuit out of your business. Lately a lot more VPN is being used to surf completely legal porn sites. The feel good laws to protect children (like the don't know about vpn) in some states require porn sites to get a picture of someones ID. Seem the people that make this law don't care much about idenity theft.
In general you do not need VPN if you only goal is to protect your traffic. The bad guys already know all the IP of all the banks. It is more used to change your location so you can access some service that is blocked. Maybe you want to watch the BBC from the USA
Your traffic is encrypted with HTTPS which there are not even rumors that it has been cracked. All the attacks are related to replacing certificate servers which the browser detects and warns about. The second protection you should be using is encrypted DNS. Microsoft now supports this in the OS in the DNS settings. There might be more but 8.8.8.8 and 1.1.1.1 have been long time supporters. Your are in effect using a VPN tunnel but using HTTPS to get the DNS server.
At this point all your traffic is in effect using a vpn, ie https, to end site and the DNS server. At best the bad guys could see the IP address you were accessing and if they somehow already knew where you were located and had you source IP they would know that. Not much real useful. At best they might figure out you liked to read tomshardware and watch netflix.