No worries, you are welcome.
To answer your first question, correct, without that option, rule would not work.
As far as 2nd question, I still dont understand myself what this option actually does. 3 years ago, I had case with TAC with RA issue and T3 guy asked us to enable this setting for back connections and when I asked him to logically explain to me what it does, he could not and said would ask esc. buddy, but that sadly went nowhere as far as good explanation.
Below is what it says in the dashboard, but honestly, I cant "digest" it to understand it in layman's terms, if you will.
Back connections
Usually communication with remote clients must be initialized by the clients. However, once a client has opened a connection, the hosts behind VPN can open a return or back connection to the client. For a back connection, the client's details must be maintained on all the devices between the client and the gateway, and on the gateway itself. Determine whether the back connection is enabled, and the frequency of the Keep Alive packets sent by the client in order to maintain the connection with the gateway.
Best,
Andy