Extra events is the sixth tab on a conference, between Presentations and Registrations. Some conferences also list them on their own website.
Check the tab again nearer the dates. Extras are usually announced with the programme rather than when registration opens.

What is offered depends on the host institution and the city, so it changes every year. Nothing here is guaranteed at every conference.

Two extras recur across conferences and both are online, which means neither depends on being in the host city.
If you are attending online, these are your social programme.

Likely too early. Extras are announced with the programme rather than when registration opens — look again nearer the dates.
Yes. The welcome and training session and the talking circle both run online, and for an online delegate they are the social programme.
It depends on the conference and the event. Where a charge or a booking applies, it is stated with the event on the Extra events tab.
If it is your first CGScholar conference, yes. It covers finding your way around and putting media on your profile — the things this guide describes, demonstrated by a person.
Not necessarily. They depend on the host institution and the city, and both change from one conference to the next.