New to using WPforo & not a techie, please help with the following.
Thanks so much. I appreciate your help in advance.
Please make sure your admin email address is included in the forum admin email addresses field. You can check it in Dashboard > Forums > Settings > Email Tab.
The FROM email address of your forum is also set on the same admin page, make sure it looks like email@example.com. Don't set it the same admin email, and make sure it's your domain email address not gmail or something else. The domain email address increases trust of email receiver servers and make it more possible to deliver to inbox not to spam-box.
If the new topic creator has the same email address as the receiver admin the email may not be delivered. wpForo doesn't sent email notification to the topic owner. The owner already know that the new topic is posted by himself. So always test with other accounts.
And please check all these points one by one, they explain the possible issues when emails not sent: https://wpforo.com/community/faq/not-receiving-automatic-replynotificationconfirmation-emails/#post-5344
2: Is there a way to default everyone to be subscribed to topics/posts so they get notifications by default & if they don’t want it they can opt out later?
I'm sorry but there isn't Users should subscribe to get email notification. To make them automatically subscribed to own topics I recommend enable the "Topic subscription option on post editor - checked/enabled" option in Dashboard > Forums > Settings > Features Tab.