Getting rid of rust on cassette and chain

Hey all, very new to bike maintenance (only changed a tire once so far).

My chain and rear cassette are pretty dirty now, maybe even some rust. Not totally sure if it’s rust or just gunk. The bike hasn’t seen much bad weather except one snowy ride, which might’ve caused it. I’ve also never lubed the chain before, so it’s long overdue since it’s getting noisy and doesn’t feel smooth.

I want to clean everything properly and switch to Silca drip-on wax that I just bought. I’ve seen people mention mineral spirits or alcohol for cleaning, but not sure what’s actually best and safe.

What would you recommend for a proper first deep clean to get things back to baseline?

Is it better to just change a chain at this point?

Thanks, appreciate any help!