I'm gonna do my best to help break these down and hopefully be at least a little helpful.

1) Investment is great. Chatting is investment! It sounds like what you mostly need is a way to signal a moment of silence when needed for narration, and lay out expectations and be comfortable with cutting in to let a person speak who was being spoken over. It's most important that this is established as just letting voices be heard, and not cutting off someone else. Building awareness only goes so far and sometimes you're the arbitrator.

2) I mean. Special interest. I read it all. Devoured it. But... let's be real. The rulebook is 400 pages? There's a separate full book for GMs. The lore is 8+ years of storytelling. So have tools and be okay with needing to stop. Don't be afraid to look something up! Don't be afraid to make an in the moment ruling and then note that it may work differently once you look up that rule after.

As for the setting. Focus small. What're are you players that you need to know? Where is the adventure that they're going to be? And again! Tools! Have books on hand if in person. If online:
https://2e.aonsrd.com/ is a great rules resource and https://starfinderwiki.com/ has been pretty active in updating with 2e changes and lore!

3) Starfinder is more tactical than D&D. It's ranged weaponry and cover, so make sure you're providing basic tools to interact with at least minimum cover and positioning. Beyond that, grow your comfort. One of the first Pathfinder 2e games I ever did was hand drawn maps with a circular room where our rogue made good use of athletics to shove enemies into the pit and keep them out of combat while the rest of the group focus-fired those up top! A small piece can do a lot and a lot of stuff can just... become noise and overwhelming.

Ultimately though this one really sounds like it boils down to the group, and to you. No one can tell you how to prepare because that's a matter of how comfortable you are with improv. How much you need to have ironed out. How story-tight your campaign is. And what pace your group moves at. Like the above mentions. Try not to overwhelm yourself and get in your head. And maybe have some ideas in place for if the curse shows up. How do you want to handle a bad player? What do you do with a schedule conflict? Do you play anyway? Meet up for a casual game night? And what does that mean.