Yeah, there's no intro for the convo. They can start off with pretty much anything - my first question was a really straightforward 'Können Sie Ihre Familie beschreiben?' but some of my friends' conversations started with stuff about free time or school.
Some good advice for the oral is just not to over prepare it. I know people who spent ages memorising responses word for word, and as a result they kinda sounded like robots, and if they forgot anything/were asked something they didn't expect, they lost their place or froze up. So it's good to write out responses and stuff, but remember it's important to be able to sound natural. Plus you're always gonna get stuff you're not prepared for, so you can't rely on just memorisation - it goes almost without saying obviously, but your German will need to be good enough to improvise and sound natural. Practice speaking as much as you can
Also for the detailed study, try to include a lot of opinions in there as well. They like you to actually analyse the topic rather than just spout facts, so it's good to chuck in some stuff like that. My topic was about German children's literature and how it mirrors changes in societal values over time (particularly in relation to raising children), so I was able to compare contemporary value systems with old fashioned ones and which I think are better, and whether the older stories and new stories were better for teaching kids morals. So yeah opinions are great, use a bunch of them.
Hope that helps a bit haha
Viel Erfolg!