Again, thank you so much for taking the time to write this, really appreciate it. Glad to know the physics appeal to you now, your feedback on the earlier demo was crucial to help me rework it. About the pause bug, thanks for pointing it out, I'm aware of it but I need to fix some things with how different systems handle input to have this sorted (I know a way to duct-tape it for now, but don't wanna take that route).
I'll give more details on your other queries in some time, because there're several things in the gameplay/progression that even I'm yet to finalize. But what I can say for sure is that the powerup system will be more similar to NFS Rivals than Blur....where you pick a loadout before a race and then go in with that (no pickups like Blur). Also there won't be a proper story, but there will be some level of world-building and vibe in terms of rivals with personas who will interact with you during races and campaign. The closest inspirations for these would be Road Rash PC and Midnight Club 2. They don't exactly have a story, but you do have some banter and narrative with your rivals as you progress.
Finally, I'm thrilled to hear you also wanna build a game! What's it gonna be about?